The Accursed Blade (by Stephen)
The Accursed Blade was forged by a powerful race of sorcerers long ago, during an ongoing war between his people and their ancient enemy. These sorcerers had magic so powerful it made them seem like gods to ordinary races. To save themselves the actual battle they gave these blades to the lesser races.
These blades appear to be crudely forged daggers. Detect magic will find a powerful magic that is beyond the player's ability to figure out what it is. They vibrate slightly and are intelligent.
In combat the blade will assess the situation and alter reality to it's own advantage. First of all the blade blocks the enemy's ability to sense danger if the user is planning a surprise attack. Secondly it blocks the enemy's ability to use magic. It cannot block magic completely but can take care of magic below level 5 spells. Thirdly it analyses the enemy's strengths and weaknesses and employs the minimum required force. This can have interesting results.
One example is that a young elf was play fighting with his brother, the blade took this as actual combat and saw that the opponent had a dagger. It therefore changed into a longsword to win. This action ran the other brother through. The butler, believing this was murder in order to be the sole heir, set it up to look like marauding parties had done it.
A second example is that an assassin was fighting a mark who had a longsword. The blade therefore became a bigger sword. This sword, however was too big to hold so the blade had the assassin gain another set of arms. The assassin died from the shock of finding that he had four arms. It can also check the memories of the enemy and use them against them. For example if the enemy is afraid of something it may turn into that.
The blade can also turn into a creature if the situation warrants it. An example is that when fighting a large immensely powerful dragon it transformed into a duplicate of that dragon.

If the blade encounters one of the ancient enemy it will be relentless in killing it. It will attack without provocation, even if it is helping the user of the blade (for the sake of this the ancient enemy can be anything you want it to be).
Once the blade has a user, it is hard to get rid of unless the blade deems that changing owners will facilitate it's hunt for the ancient enemy. It has been known to take the place of one of the user's possessions, such as a pipe.
The blade is extremely difficult to destroy, for reasons that should be obvious. Feel free to however. Good Luck. Maybe a large group of powerful sorcerers could dispel the magic, but first you would have to incapacitate it.
Incase you were wondering I got the idea for this from the 6th book in the death gate cycle: Into the Labyrinth by Margret Weis and Tracy Hickman.

Boomerang Shurikens (by Kurtis Swekla)
These magical shurikens cause 1 point of damage (just like regular shurikens) but when they hit their intended target, they automatically return to the thrower. However, if they miss their intended target and hit something else (another creature, wall, etc.) then they simply cause their damage and fall to the ground or remain stuck in the target.

Chain Lightning Sword (by Kurtis Swekla)
This broad sword does not appear unusual or magical in any way. It will be detected as magical with a detect magic spell however. When a character uses this sword it causes normal broad sword damage plus 1d8 lightning bolts that cause 1d6 damage each which appear to spring forth from the blade, where the blade meets the handle and hit the enemy.

Darkflame (by Paul)
The Darkflame is constructed of obsidian and radiates magic. It is a +2 magical weapon and does normal long sword damage. However, upon contact with an enemy, the sword also casts Burning Hands as a 10th level wizard. The creature struck can save against the spell; one with magic resistance may even ignore it.

Death's Edge (by Tim The Red)
A sword with a black blade created by the Demon Memphose, able to speak inside the wielder's mind it was dismissed by Memphose because it's alignment was Good. It gives the wielder a +10 bonus to hide and move silently it will return to the owner if it wills it to do so. The sword is = D12 18-20/x3 5lbs medium sized sla

Death Summoning Sword (by Kurtis Swekla)
This black bladed broad sword emits a very high level of magic. When the wielder attacks someone, and hits with the attack, he causes normal broad sword damage and a black cloud comes out of the end of the blade and surrounds the blade. The next time the character hits with the sword, it causes its normal broad sword damage and it kills the enemy unless a fortitude save is successful with a DC of 35, if the saving throw is successful, then the enemy only takes the regular broad sword damage and the enemy could still die if the damage sustained is enough to kill him.
You could add a certain number of charges in the sword if you think it is too powerful of a weapon.

Fire Bow (by Kurtis Swekla)
This bow is elaborately carved with shapes that look like flames leaping around on the wooden handle and it is the colour of and orange flame. Whenever someone shoots an arrow from this bow the arrow is lit with fire as it flies towards its target. Upon impact the target is lit on fire and takes the arrow's impact damage (usually 1d6) plus 2d6/round for fire damage. The fire will burn up to 10 rounds or until it is put out, which ever comes first. The fire can be put out by magical means only (special water, or a dispel magic spell). If the arrow that is shot has magical attributes (such as poison) the arrow will also have these effects on the target. But something like natural poison will be burnt off by the magical fire and will not have any effect on the target.

Greatsword of the Dragon (by Nick)
This blade is so strong only a half dragon can wield it. It does 4D12 damage plus the damage of the chromatic dragons; Fire(Red dragon), Acid (black dragon), lighting (blue dragon), Acid mist (green dragon), and Cold (white dragon). All are at greatwyrm power. Look in Monster Manual for dragon damage. Physical Description: The handle's tip is extended into to short points, the handle resembles a dragons tail, the top if the handle is a red-gold hand guard that looks like a dragons head, the blade is long and resembles a greatsword.

Insulting Rapier (by Kurtis Swekla)
This ordinary looking rapier, causes normal damage, but any time the character attacks, the rapier makes insults at the character like, "you hit like a woman," whether the character hit or missed with his attack. This idea was given to me by someone on a message board, but I don't remember his name, you know who you are probably, and thank you for this idea, I had great fun with it.

Leo's Blackfire Katana (by Alan Hall)
This sword is of 42 inches in length it is two handed though light enough and perfectly balanced to use one handed. The sword itself was a normal katana until it was specially blessed and enchanted by seven different wizards, two of those were believed to be Elminster and greyhawk themselves. It allows its wielder to strike for 1d20 damage and 2d20 vs. vampires. The Blackfire Katana is believed to be able to cut through any known armour to exist except for mithril.

Short Sword of Curing (by Robert Ingebrigtsen)
This short sword was made by a peaceful but self-conscious bard. He hated violence, but loved epic stories. Thus he created this blade to be able to enter fray and not kill an innocent creature. He then was able to fight like a hero!
The sword functions as a normal short sword, dealing normal damage. It casts a Cure Light Wounds on a successful hit. This heals 1d8+1 hit points. Also, feel free to add more, minor effects (peaceful ones, though) to spice up the sword.
Note: It might be a bad idea hitting yourself to receive healing- the original player did so, rolled a natural 20, and cut his own leg off...hilarious for the rest of us, but maybe not for him.

Skeleton Red Sword of Life (by Kurtis Swekla)
This sword is usually found wielded by a skeleton. However if a living character tries to use this sword, they turn into a skeleton. That is, they only are a skeleton in terms of physical characteristics (the character is only composed of bones). The character still has control of his body and can think on his own, he can talk and all his senses, abilities, and skills remain unchanged. The character retains his hit points, etc. and the only thing the character can't do is change his body shape into something else (by way of a spell, power, or magical item). If the character puts down the sword he remains a skeleton, the only way to change back into himself is to have a dispell magic spell cast on him, against a level 18 wizard. The sword itself is a bastard sword with a damage of 1d10 + 15 special damage. This special damage is caused by its magical effects, it seems to suck life out of creatures when it hits them (this is the extra 15 damage) and the creature feels a cold wind go through them when and where the sword hits.

Songblade (by KC)
This item looks like a broadsword, with about 50 gems set along the blade and in the hilt. It doesn't do damage, having no edge, however, unless you count the 1d2 bludgeoning damage you can get from anything when you hit someone with it. One holds the song blade like a guitar, the hilt in the off-hand, and the blade in the other. By running your fingers over the correct gems you produce beautiful music sounding as if it comes from dozens of different instruments. With the Songblade selected as an instrument of choice under perform, you get a bonus of +10 to your perform skill.
Item cost: 2000 gp.

Sword of Health (by Kurtis Swekla)
This sword looks like a normal long sword except that it as a red gem (possibly a ruby) on the pommel. This gem glows bright red when a character stabs or slashes an enemy. However, contrary to what one would think, this long sword does not cause any damage to the enemy, it in fact heals the enemy by 1d8. However, whenever this sword does contact an enemy, it does make an illusion that it causes damage. When it slashes, stabs, etc. into an enemy it produces illusion of a wound that looks life-like in every way, except that no blood pours out of the wound (this could be one of the indications to the character that this sword is not causing any damage).
When a detect magic spell is cast upon this sword it is highly magical.

Vampire Sword (by Jeff Neeser and Kurtis Swekla)
This sword is a long sword which has a crimson rain drop mark on both sides of the blade. When a character hit an enemy with this sword, he causes 1d8 damage, but the character instantly gains those wounds caused to the enemy, as if he was healed by spell. The sword can not "store" wounds to give to the wielder, that is, if the character has taken no damage (has full HP) and hits an enemy, he will not gain HP's above his maximum, nor will he then gain those wounds after he as taken damage.