Xsystem is a filebrowser by hacker013.

Release notes:

Include:
– File Browser.
– JPEG viewer (gba-jpeg) (max size 256 * 256).
– Brainfuck Interpreter.
– Text viewer.
– GUI (woopsi GUI).
– NDS launcher (Link’s rebootlib).
– Calculator.
– Debug Console.

http://forum.gbadev.org/viewtopic.php?t=16084