The ATI 5770. It says 2009 or 2010 but it works fine on my machine.
I'm a Final Cut Editor, though, not a gamer. So I can't say if this card would make them happy. For me the speed of the hard drives matters more, honestly. The times I wait for stuff is video compressing. Just plain old cutting and real-time filters were never a problem even before this. But waiting for that DVD to compress while the processors work at 40%...that's always been my headache.
I'll tell you the 2 places I noticed the biggest improvement with the video card upgrade: Safari and Aperture scrolling. I figured Aperture would get better but I was amazed at how much Safari improved. I hadn't realized how much my video card was holding up my web experience before.
I haven't gotten an SSD yet. That's next on my list but funds dictate I'll have to wait a little while longer. But I can already feel my machine breathing easier, I know that'll just kick it up another notch.