Here are some ideas that I don't think other dashboards have (yet) - not sure if some are actually possible, but I'm sure there are ways around them
Button re-configuration - A feature that lets you change which button does what, like re-mapping the 'B' button as the 'A' button (and visa versa) so that you can get around pre-set configurations within games and you can choose your own (and possibly automatically loading the specific configuration for a particular game when it is loaded up) - although this idea might be more suitable for a BIOS - Xenium OS perhaps? Also, would it be possible to change the sensitivity of the analog sticks/buttons?
Manual/walkthrough support - Simply a folder that contains manuals/walkthroughs etc. for a particular game and when that game is highlighted in the menu you have the option to press a button and bring up the manual for it or a guide if you're stuck
Quick choosing - This is just an idea to speed up the selection of certain features. Could you make a menu that lets you assign a button to programs/options as soon as the dash starts so that you just press the button and that menu pops up? E.g. Pressing 'Y' automatically opens the 'Games' folder, pressing 'white' opens the DVD drive or pressing 'X' launches an emulator etc etc. This obviously depends on what buttons have already been assigned to other dashboard features.
Tell me what you think and if you'll implement them, I'm sure I can think of some other stuff too!