My vote is for the Zalman Extreme - $65, big and cool looking, very quiet, blue LED fan, and keeps it cool (3.68ghz OC, max burn test temp is 57C). Tho there's obviously many good performance coolers to choose from. Check out some reviews.
I 2nd the CM hyper 212 plus. I guess it just depends on what you're planning on doing. If you're going to do some extreme OCing, you may want to look at others, but I seem to remember seeing some people OC pretty well with the 212. I've got awesome temps with a mild OC to 3.4ghz on my i5 with temps around 31 idle/44 load.