Unless you're hard over on nVidia, the 7970s are a little more than a 670 and come with Assassin's Creed 3, Hitman: Absolution, Sleeping Dogs, and 20% off MOH: Warfighter.
If I was buying today, that would be my pick (not that I don't love my current card!).
Edit: BF3 runs close to 60 with dips to around 50 on ultra 1080.
Ehh, none of those games really appeal to me. But a free Borderlands 2? Heck yes. Anyway, can you point me to a good 680 that's < $500 or a 670 that's just as viable, or are you more experienced with AMD?