Not sure if it's been mentioned yet, but: Emulation.
I know I've seen 360's that can support it, and I'm not sure about PS3's, but Emulation both started and is at its strongest on the PC. And you wanna talk about true gems that are neither graphically astonishing or requiring a $3k computer to run, go no further. I have a 5-year old laptop, 512 MB RAM, about 1.6 GHz processor, and it can run SNES, N64 and PS1 Emulators without fail. If not for Emulation, I'd never have been able to play Earthbound, Xenogears, Seiken Densetsu 3, Banjo-Tooie, Conker's Bad Fur Day, the list goes on.
Not only is Emulation a great way to access the gems of the past, but it's also a VERY cheap way. Like I said, you don't need a whole lot of processing power to run emulators - a modern bargain-bin computer or equivalent older computer will do - and pretty much all of the ROMs on the Internet are completely free. I'm sure there will always be the nagging uncertainty of legality when it comes to emulation, but then most sites are pretty clear on what they can and can't offer. For instance, I believe ever since Nintendo started releasing their older games in their WiiShop, most ROM sites have had to take down various Mario and Donkey Kong properties. But that's a drop in the bucket compared to how much else is out there! If there's an older game you've always been wondering about, grab an Emulator, the ROM, and a PC Controller and have fun!