Joining the closed beta wagon today is CS:GO. Much like the DOTA 2 closed beta, all you have to do is fill in a survey and you could stand a chance getting into the beta. Once you get into the beta, you will of course receive beta keys to gift to your friends on Steam. They will be making their first selection from the survey next week, it will make up of 1.6 players, CS:S players, and players who have played neither.
To stand a chance to get into the beta, all you need to do is enter this into any Windows Explorer or browser address bar and it will open the survey through Steam for you: steam://takesurvey/2/
Image source: http://www.pcgamer.com/2011/08/12/valve-announces-counter-strike-global-operations-playable-at-pax/