I'm a big fan of gog.com and try to buy my indie games through them as I like their anti-DRM ethic. There's one game I would love to see available on there, and though I know it'll never end up being available because it's an EA game, I can still pretend.
I'm from Rugby League country, it's my sport of choice, and it has never been a sport graced with high quality games. ARL 96 on the PC was amazing, though. It was the sensible soccer of rugby league, and I have spent countless hours trying to hunt it down online in recent years so that I could play it again, though sadly to no avail. The game CD is incredibly rare now, most of them being in Australia, so it looks as though my dream of playing this game again will never be fulfilled :(
If you could pick one old game to be sold on steam/gog/whatever, what would it be?