Diablo-style weapon drops, where different weapons have different fire rates, damage, special effects, altfires, etc. And once you're done with a weapon, you can drop it, or throw it and make it explode. You lose all the ammo it had, but the more ammo you drop it with, the beter the bang.
Trying to think of a sane way to do that kind of thing with ZDoom is the hard part.

