Mods are great. The best Tribes games were mods, the duct tape mod fixed Doom 3, and Half-Life was essentially a Quake 2 mod. Well, not really. But you get the idea. Not all mods, however, are level packs or hacked weapons and dialogue. Some are simply unexplainable. Cat-Life?
This list of really weird mods is pretty fun, although 6 is a pretty low number to choose when you’re looking at weird mods — especially when two of them are Left 4 dead sound packs (snap into a slim jim!). I’d say where are the subtly weird ones, like a mod that re-enables Aeris in FFVII? That’s weird because the people who want it are creepy. There’s a whole world of mods out there — start at the beginning, then look at the ones out there for Crysis and stuff.