Minecraft Bukkit Plugin for various test things, all should end up making a nice gameplay addition.
/witchtower projectile - Summons a ball that will follow you around.
/witchtower shoot - Summons a ball targeting looked block/entity.
For both commands, the ball explodes when getting near its destination or going in a block.
/witchtower tower - Generates a big ugly cobblestone tower.
/witchtower witch - W.I.P.
Right click with magma cream = do /witchtower projectile
Left click with magma cream = do /witchtower shoot