Here are a few short stories I have written, nothing special but worth a read.

Hunted The crew of a ship are attacked by a mysterious being, causing shipmates to doubt each other and turn on their former shipmates...

Betrayal A routine Space Hulk cleansing turns into a unexpected attack when the squad find something hidden in the depths...

Other peoples work:

The Truth of the Horus Heresy An interesting piece on the Horus Heresy from the side of Horus. By Jason Dillingham

Starting a Resterant in the world of 40k A compilation that if I remeber correctly was on the Maelstrom Crew's old forums, a kind of complation.

A Chaos Space Marine's Diary From the flame valleys thenselves (GW boards) comes this amusing story of a Chaos Space Marine's life for a few weeks. By xenofexx.