Boycotted Activision AND Blizzard for being associated with them. I still play Diablo II, but Starcraft 2, Diablo III are off limits, and World of Warcraft would be if the monthly subscription didn't already turn me off.
Even old school Activision titles that are on Impulse/Gamersgate/Good old Games I won't buy, even if I'd really like to, like Caesar IV.
Straight up anything with Activision or Blizzard anywhere in the product description, I won't pay for, unless it's a compilation disc with a non-Activision game I want.