I'll throw one out there. There was an idea that we floated around for a while at my old clan that we never really got off the ground that would be cool to see implemented: an "Old School" sever.
The idea was that we would have a server, independent of our normal dedicated ones, that would host a rotating list of various retro games. It would cycle to a new game after a set amount of time (1 week, 2 weeks, 1 month; we never really came to an answer on that). As far as a roster of games, our clan thought about running stints of former divisions/games that we no longer had dedicated servers for; think Unreal Tournament 2004, Quake III Arena, R6: Raven Shield (and other Tom Clancy-series games), Counter Strike 1.6, Team Fortress Classic, various Call of Duty, Battlefield/Bad Company, and Medal of Honor titles, and then games that just had old school deathmatch/multiplayer stuff that we enjoyed like Duke Nukem 3D, Alien vs Predator 2000, Turok 2, etc.
Granted, it would need to be tailored to games that multiple people here would both own and want to play. It was never something we could get off the ground because we couldn't find consistent player numbers for, but I think it would be cool to see if the support was there.