Getting back on topic, another thing I have that is rare is The Neverhood for PC, Disc only. I have had this game for a long time, even before my first system, and it turns out to be worth around $50, and I love the game. Its a point and cliker, with claymation graphics and It has one of my favorite game soundtracks. I think it is now freeware, so it is worth a download.
Man, The Neverhood! My uncle had that game when I was younger. He was the first member of my family to buy a computer, and that game came in a bundle with the system. I remember him describing it to me, like, "You'll love this game! The guy gets his head knocked off, or gets eaten alive, and you never run out of lives!" I never got too far in the game, but I loved playing it. Thanks for reminding me about that one!
Skullmonkeys, if I remember right, was panned when it came out. I have an old issue of Game Players where they review it - their biggest gripe was that the game was very well-animated and controlled well, but that it was essentially a cookie-cutter platformer. I guess they were expecting more from it, given the game that came before it. I never played Skullmonkeys, but I probably will, one of these days.
Also, on the subject of repros, I **highly** recommend ocdreproductions.com. Kody K., who runs the site, is a real nice guy, and gets orders out fast. He also takes requests, which is how I got my copy of Tecmo Super Bowl 2012 - I designed the label, myself, and he printed it on the cartridge after he burned the game. It's honestly and truly one-of-a-kind, and is definitely my most prized non-retail game.
If I ever get around to posting a pic of my itty-bitty collection (I have 32 games total, across 8 different systems) I'll be sure to show off the custom cover I made for that one. I'd upload it to the site if I thought anyone would actually download it, but I'm pretty sure that one's something that only I'm interested in. Oh, well.
Glad to see this thread getting back on track! It's such a great idea, and I've really enjoyed reading everyone's responses so far!