Fighting fans don't have too many options on the PSP. Guilty Gear Judgment takes ARC System Works' awesome 2D sprites and puts them in the palm of your hand. This PSP fighter includes 20 characters, multiple gameplay modes ... and can be found for cheap at Circuit City. $13 (plus shipping) will allow you to take the game home.
The game received generally favorable reviews, earning a Metacritic score of 78.