The Head of Vecna is my all time favourite funny D20 tale. It shows exactly why the GM can never underestimate player character stupidity.
The Dingbat stories by those guys. A very 1st edition AD&D group. Laugh along with the Paladin and the Ranger as they see how much abuse a Monk can take. Get advice from the bitter mage Saramud.
The Saga of Aristobulus, the Dark Book I, Descent Into Darkness by Jeff Standish and Dreamwalker is a tale of a very depressed Elf who journeys to the Underdark.
The Saga of Hawn Ambrosius by Jeff Standish is a more serious story about an Elf`s quest for vengence.
The Navero Tales by Dan Parsons. Follow a naive cleric's journey from 1st to 6th level. Written very much like a game in text.
The Wizard of Smaug by Bruce Norman. About a man who wanted to learn how to blow things up.