A bunch of new WADs are available for Doom for the PSP, courtesy of michalt441. There are four mods available: Duke Nukem, Quake 4 and Quake 2, and Fistful of Dollars (based on the movie of the same name, starring Clint Eastwood).

Michalt441 has personally tested all these games and remarks that they work, although some of them crash sometimes. Michalt441 promises to release a compilation of even more WADs for Doom in the future so you can watch out for that one.

Here are some notes before you get all gung-ho. The Quake 4 mod only has one level available, while the Quake 2 mod replaces 10 entire levels for the game. Ok, there, go gung-ho. Remember, these are known to crash units so be careful when using them.