Get a copy of Tailgate Party while they're easily available. I freaking love that game. Games don't need to be magnum opus masterpieces like Battle Kid, just a novel idea that happens to work very well. Streemerz (Action 52: Volume 1), Alfonzo's Arctic Adventure, Black Box Challenge, and Cowlitz Gamer's Second Adventure are some more very high quality games that haven't been mentioned yet, although they're mostly available cheap/free as ROMs. I can't think of TOO many games that are top games, locked to cartridge, and haven't been made available for digital release.
Check out the currently available homebrew thread:
http://nintendoage.com/forum/mess...