Flash Advance Linker (XG2, EZ2, Flash2Advance, EZF Advance) is a device for Gameboy Advance (and GBA SP) game rom backup. GBA Flash Advance Linker connects to the printer port or USB port of your PC. When connected, it can Read and Write GBA game ROMs from or to the plugged in game or Flash Advance Card so letting you play rom files that you have on HDD in GameboyAdvance.
Im looking to buy one of those, I gotta back up some games
You can play old Nintendo Games, MP3's, save pictures etc.. It's like having a operating system on your GBA!
Here's a link for more information,