Okay, and after reading all 9 pages, I have to add.. (Since I can't edit.)
If what Vice Guy said is true, then I also have that same XONOX Double-Ender, Artillery Duel/Spikes Peak.
Also, I have a copy of the NES Miracle cart. No keyboard, though. I picked it up yesterday just because I was sick of seeing it in the bin every time I went to the GS.
A while back I passed up Herzog Zwei for Genesis only to find out later it was rare. When I went back, I found some guy going through the bin for EVERY GAME HE DIDN'T ALREADY OWN. Fucking bastard. Glad he wasn't local.
Other than that, I do have all three SMB games boxed complete. Including the NON-Duck Hunt version of Super Mario Bros. $.29 at GS.
I'd have to see a rarity list to see what else if anything, I have that's rare.