I might be alone in this, but I found a pretty interesting fan fiction based on Dragonball a couple months ago. It's call Dragonball Multiverse. It takes place after Dragonball Z (author refuses to acknowledge GT at all) and is pretty much a sequel series. The story is about a tournament in which multiple universes are brought together for a tournament and the winner gets a wish from one of the universe's Namekian dragonballs.
Screw the story, what this is really for is to see some interesting alternative universe set ups. The original universe (from the anime/manga) is universe 18. But there are other interesting ones, such as one where Frieza won, another where Cell killed Gohan, one where Majin Buu literally absorbed everyone of power, and one where Goku never became Goku and conquered Earth.
It's still ongoing, and is done in manga format with pages being uploaded every one or two days. The main story is periodically interrupted for a special explaining the differences in some of the universes. Currently, knee deep in a special explaining how Bardock became a Super Saiyan in universe 3. I'm actually enjoying it quite a bit. Partly because it explores ideas I had always wondered from the series.