I have some REAL ideas, how about hacking some of the Assault Suits games for Super Famicom. Also how about hacking the Mickey Mouse's Magical Quest Trilogy, you could do a LOT with either one of those games, new levels, possibly new abilities, or put all the abilities in one game etc. put all the characters in one game, make sprites for Donald in the gear from I and II, and sprites for Minnie with gear from I and III. for Assault Suits you could make new levels, you could make sprites for new mechs (you can also maneuver with Front Mission: Gunhazard which is essentially an Assault Suits game) you could make new weapons or add ons like shoulder rocket launchers etc.
They both have a bunch of potential. I'm not asking someone to do them for me because I am to lazy, but if someone REALLY wants to hack but has no ideas, well here are some dandys if you ask me.