Hello. I have a friend looking for bukkit plugin that can make a bridge appear/disappear. We found one already http://dev.bukkit.org/server-mods/retractablebridge/. But that isn't exactly what he's looking for. We're talking about a realistic looking bridge that can be retracted. An example would be VoxelBox's VoxelTronix plugin that's still in development. If someone could refer us to a decent plugin that let's us make a bridge appear/disappear, thanks.
Try looking into something that would modify how pistons would push a block. Other than that I haven't seen anything.
