Right now, it can change your avatar colors, unlock achievements, add games, view/edit STFS packages, and mod 2 games (WET and Castle Crashers). The final release will mod over 15 games and have some other features. Edit: Here's a video that somebody made: http://www.youtube.com/watch?v=SXlKFe27R0o
You can do it on your dashboard as well. In CoD4/5, use ^# to make your name have colors. The first few hex values will also give you button images. 01 = A 02 = B 03 = X 04 = Y 05 = LB 06 = RB 07 = LT 08 = RT 09 = LS 0A = RS 0E = Start 0F = Back I might have made a mistake. 4 of them should be for the D-PAD as well. Can't remember completely off the top of my head. Colors are as followed: ^^0 = Black ^1 = Red ^2 = Green ^3 = yellow ^4 = blue ^5 = light blue ^6 = purple ^7 = white I forget the rest. google should help you with that. In parties, the buttons will appear as the unknown symbol square [].