I don't really "boycott" anyone per se, but I sure as hell don't like the Online Pass system that most companies now employ.
That said, for most game developers/publishers (EA/Ubisoft etc.) at this current point in time, the only products I'll buy from them are those under a particular franchise name, or if a particular game catches my interest enough.
EA: SSX, Burnout, Need for Speed
Capcom: MegaMan (though after their cancelling of Legends 3 and effectively the whole MegaMan name, they might be the closest to a proper boycott from me, mainly because nothing else they provide tickles my fancy)
Ubisoft: Rayman, though I might consider grabbing Assassin's Creed III on the Wii U if it intrigues me enough to look past their business practices (Online Passes and DLC that should be in the game from the start)
Activision: Currently, only the Spider-Man games, particularly the three most recent ones developed by Beenox. And I ain't buying the World of Warcraft expansions that I don't have until I get off my lazy ass and contact Blizzard about them getting my account unbanned because I got hacked months ago. Though I have found myself growing increasingly curious of Diablo III.
At the most basic level, I'm more or less on the same field as the "vote with wallet" crowd. If I like, I'll buy... eventually. If I don't, I won't. One less person buying games isn't really going to make companies like EA rethink their business model, anyway, as they make more than enough money as it is.