Insightful (General)
You gain more from your experiences.
Prerequisite: Wisdom modifier +2.
Benefit: You gain a 5% bonus on all earned experience points from now on. XP already earned and XP gained magically, such as from a magical tome, does not gain this bonus.
Special: You may choose this feat more than once, one more time for every point of Wisdom modifier above +2. Thus, with a 16 or 17 Wisdom (+3 mod), you may take this feat a maximum total of twice. When chosen multiple times, the effects stack.

Epiphany (General)
Sudden insight grants you greater competence as an adventurer.
Prerequisite: Wisdom 14+.
Benefit: You immediately gain one character level. If you are multiclassed, you must choose which class advances in level. Whether you are multiclassed or not, you may choose to invest this level in a new class. You gain all class and racial abilities associated with your new level, including hit points, attack and save bonuses, and so on.
Special: You may choose this feat more than once.

And a series of similar feats:

Acid Balm (General)
You can be healed by the cleansing power of acid.
Prerequisite: Natural resistance or immunity to acid damage, not resistance or immunity granted by items, spells, powers or other outward sources.
Benefit: Once per day, you may declare use of this feat. When you are subjected to an acid attack, you are healed 1 point for every 3 points of damage the attack would normally have caused a creature with no damage resistance, acid resistance or immunity. You may elect to voluntarily fail your saving throw against the attack to get the maximum benefit. Declaring the use of Acid Balm is a swift action that does not provoke attacks of opportunity, and its use may be declared even if it is not your turn.

Bioelectric Feedback (General)
You can be healed by rechanneling the power of lightning.
Prerequisite: Natural resistance or immunity to electrical damage, not resistance or immunity granted by items, spells, powers or other outward sources.
Benefit: Once per day, you may declare use of this feat. When you are subjected to an electrical attack, you are healed 1 point for every 3 points of damage the attack would normally have caused a creature with no damage resistance, electrical resistance or immunity. You may elect to voluntarily fail your saving throw against the attack to get the maximum benefit. Declaring the use of Bioelectric Feedback is a swift action that does not provoke attacks of opportunity, and its use may be declared even if it is not your turn.

Healing Flame (General) [modified from Races of Faerun]
You can be healed by the purifying energies of fire.
Prerequisite: Natural resistance or immunity to fire damage, not resistance or immunity granted by items, spells, powers or other outward sources.
Benefit: Once per day, you may declare use of this feat. When you are subjected to a fire attack, you are healed 1 point for every 3 points of damage the attack would normally have caused a creature with no damage resistance, fire resistance or immunity. You may elect to voluntarily fail your saving throw against the attack to get the maximum benefit. Declaring the use of Healing Flame is a swift action that does not provoke attacks of opportunity, and its use may be declared even if it is not your turn.

Icelacing (General)
You can be healed by harnessing cold energy to re-knit your tissues.
Prerequisite: Natural resistance or immunity to cold damage, not resistance or immunity granted by items, spells, powers or other outward sources.
Benefit: Once per day, you may declare use of this feat. When you are subjected to a cold attack, you are healed 1 point for every 3 points of damage the attack would normally have caused a creature with no damage resistance, cold resistance or immunity. You may elect to voluntarily fail your saving throw against the attack to get the maximum benefit. Declaring the use of Icelacing is a swift action that does not provoke attacks of opportunity, and its use may be declared even if it is not your turn.

Soothing Strains (General)
You can be healed by the vibrations of a sonic attack.
Prerequisite: Natural resistance or immunity to sonic damage, not resistance or immunity granted by items, spells, powers or other outward sources; must not have tremorsense.
Benefit: Once per day, you may declare use of this feat. When you are subjected to a sonic attack, you are healed 1 point for every 3 points of damage the attack would normally have caused a creature with no damage resistance, sonic resistance or immunity. You may elect to voluntarily fail your saving throw against the attack to get the maximum benefit. Declaring the use of Soothing Strains is a swift action that does not provoke attacks of opportunity, and its use may be declared even if it is not your turn.
Special: If you prefer cheekier names, this feat is also known as Good Vibrations.