Not a big fan of gaming challenges as it sucks a little bit of fun out of them for me, but I'll be beating games left and right this Summer, so I'll join in with a list:
1)Zelda II nes (Never really took the time to get good at it)
2) Windwaker gamecube (Was on the last stage, holy crap, about six years ago and stopped playing for an unknown reason)
3) Bayonetta 360 (cause why not?)
4) Ninja Gaiden 2 nes
5) Ninja Gaiden 3 nes (although I'm lethal at Ninja Gaiden and can beat 2 and 3, I'm not as polished on them as I should be)
6) Lego Star Wars 360 (never gave it a chance)
7) Lego Batman 360 (same as with every Lego game)

Mary Kate and Ashley Olsen's Sweet 16 Driving game PS2 ('cause I need true classic game in my list somewhere)
9) Castlevania III nes (I've never not gone the same route before)
10) Zillion II sms (Never get tired of beating this game)
Possibles
Super R-Type snes
Gradius III snes
Death and Return of Dean Cain
Twilight Princess
Alien vs. Predator snes