I didn’t make any best-of-the-year lists, but I support the idea. I also support new year’s resolutions, but I’m not going to write about mine.
But the internet picks up the slack.
FlowingData has a 5 Best Data Vis of the year list, which I’m fond of. It includes the beautiful Streamgraphs of Byron and Wattenberg. Their technical report has some fun applications of combinatorial optimization to aesthetics.
Lance Fortnow has a nice Complexity Year in Review on the Computational Complexity Blog. Unfortunately, I don’t have a beautiful illustration of Prasad’s result that Unique Games Conjecture implies semidefinite relaxations have optimal approximation ratios.
Healthy Algorithms 
Nice plots… I hope I find an excuse to use one this year!
I posted code to generate stream graphs with matplotlib on http://code.activestate.com/recipes/576633/ .
Very cool, Anand! I’m searching for a nice dataset to try it out. I wonder if there is an easy way to get at the pageviews-per-day data from this blog…