He's looking for a program that takes MP3s and makes them into a smaller file.
The only way you're going to do that is if you give up some audio quality. Download.com has this program:
DietMP3
Don't know how good it is but I've been looking for a program like this for my PSP so I'll give it a shoot too and see how it is.
Ok tried it on a couple of songs and it's very good. It took a 7.66 MB file and compressed it to 2.87 MBs without any noticable loss in quality. Some will compress better then others (a 4.41 MB only compressed to 3.32 MB) and I did compress one and lose 3 minutes of play so I don't know what's up with that but if you are looking to squeeze some more files on anything portable it's a good shot.