Help chosing an mp3 player

[Furcifer]

Hey, I'm looking to purchase an mp3 player this holiday season. Im really looking for something that can store any kind of file, and have the ability to direct link and transfer files to another storage device. Something akin to linking up 2 gameboys but instead of playing games, i could transfer files from one unit to another. Is there anything out that has 20 GB storage and has the ability to link up with other units? It would be really handy to trade files with friends as files these days sometimes make cd's kind of cumbersome.