For OF, it's already been mentioned, but Wise's catch to save Buehrle's perfecto was amazing.
Ruggiano made this great play against Lawrie a few years back:
Rajai's catch over the wall is still great, even though Pillar took away some of its luster last night:
http://m.mlb.com/video/v23858931/must-c-catch-davis-scales-the-wall-to-bring-one-back/?query=Rajai+Davis+catch
Non-OF, Buehrle himself made one of the greatest plays I've ever seen:
http://m.mlb.com/video/v7282679/clecws-buehrles-backhand-flick-gets-the-runner
Of course I also have to mention Jeter's cutoff to nab Giambi at home.
http://m.mlb.com/video/v3134880/nyyoak-gm-3-jeter-cuts-down-runner-with-iconic-flip