I use my GP2X almost exclusively for emulation... DrMDx and Squidge SNES are the main apps used.  I used to have MP3s and videos but they took up space my ROMs could be using so they had to go.  I keep one small (2MB) video and one small MP3 (1.5MB) just to show people what the GP2X can do when I'm out and about - gotta preach the word whenever possible!