This mod _requires_ modloader to work.
Just checked with a from scratch install - seemed to work fine - so it could very well be a conflict with one of the other mods installed somehow, programming-wise.
Also I didn't bother saying this since there were like no posts but I'm probably going to wait on working more on this until mod "api".
I quite like this idea, the "quality" of the staff affecting toss strength and hold time would certainly make it feel more like part of the regular gameplay and less of a random add-on. My reasoning for the redstone was the magic aspect of it with the diamond as an amplifier to magically lift the mob. I'll definitely think about this whole thing though.
Please Please Please PLEASE add a server side. I'm begging you! I love this mod and want to use it to drown my friends in lava. Even if you don't make it able to pick up players it would still be fun to drop creepers on them. SO much potential.
Very great mod I have to say, though it needs to pick up not just mobs, but blocks too. Its a great mod, it just needs some work, and yes, I know you are puting in gravity gun physics into it. And I know its WIP