I think UrT and the game Ron is developing should always be the main focus within 1up, but I'm 100% in favor of adding an additional server or two that host alternative games.
I've played COD Zombie before, and I have to say that it's very done. Fun, yet difficult to play (of course, I'm a noob). Requires teamwork for sure. I'm in favor...
What about a MOH:AA The Hidden server? SnKTank[1up] made the mod. Its awesome. Humans are on one team. The other team are Hiddens... people modified during scientific experiments. They are invisible and can move 3 times the speed of a human, but only have a knife and nades. The Hiddens always have a shadow under them, but are otherwise invisible unless holding a weapon. The best part is that MOH uses the Q3 engine, so much of the UrT server-side crap should theoretically cross over (easier to maintain something you already know). If anyone has interest in this Mod, let me know and I'll see if I can make a video...