I made a bukkit server and when i spawned it was one island and the rest was all ocean. How do i change the seed?
Well... it did work, however, it will only effect newly generated areas. Go explore a new area that you haven't discovered yet... any new chunks will be created using the new seed.
What i find easiest is just making a bunch of single player worlds until you find the one u want. Then go into the appdata minecraft folder, take the world save and put it into your craft bukkit folder and rename it to world.