Bohemia Interactive are starring in the latest Humble Weekly Sale, with several of their key titles featuring. You can pay what you want for Arma II, Take on Helicopters, UFO: Afterlight, Alpha Prime, Arma Gold and Arma Tactics. Pay over the minimum and you'll also get Carrier Command: Gaea Mission and Arma II: Operation Arrowhead (which also gives you access to the mod version of DayZ).