Not so much for the NES, let go of a lot of stuff, but Mega Man V is up there(have all 6), also Mighty Final Fight. A lot of my stuff of value is on the SNES really as I have: Dracula X w/book, Chrono Trigger, Demon's Crest, Earthbound, EVO, Final Fantasy II & III both with books+maps, Final Fight 2+3, King of Dragons, Kirby's Super Star and Dream Land 3, Lufia II w/book+map, Mega Man X2 and X3, Ninja Gaiden Trilogy, Pocky & Rocky, Secret of Mana w/book+map, Soul Blazer w/book+map, Sunset Riders, Super Mario RPG w/book, Wolfenstein3D, and Wild Guns.
I have mostly Nintendo stuff, but I also do have a Master System and I got some of the gems for that of value like Golden Axe Warrior CIB, Land of Illusion CIB, Streets of Rage, Alex Kidd in Shinobi World, Phantasy Star CIB, Ys Vanished Omens CIB, Lucky Dime Caper CIB, Wonderboy III CIB, and some others much NTSC and some PAL only gems.
I just have a bunch of older 8/16bit games and stuff from all lives of the Gameboy. I keep a list if you care to peek at it:
http://tanooki.batcave.net/gameinventory.html