There have been several hacks, yes. One was a hack for 1.63 that allowed you to do some basic skinning for the menu (mostly only color changes). Another was for 1.7 and allowed you to auto-boot a specific *.nds file upon bootup by holding a specific button combination, among other functions I can't remember at this point. However, as these firmwares are not very old, I would not recommend either of the hacks.