This is a Nintendo DS homebrew app for adding GBA files to a very specific Gameboy Advance flash card, the EZF Advance. It doesn't work on any other flash card, not even the EZF Advance II, III, etc.
To use, place a folder entitled "gba" (must be all lowercase) on the root of your Nintendo DS flash card, then place any GBA files you want to flash into this folder. Then, run this app on a DS with the EZF Advance plugged into the GBA slot, and the games will replace all games currently on the card. The file name of each game will be used as the menu title, and cannot exceed 32 characters for each game.
Enjoy!