Not sure if there is interest for this, but it might be good idea to have a thread for sharing the Steam Guest Passes back to GB community? 
   
What are guest passes?

A guest pass allows the user to temporarily share a game license with a friend who does not own the game. Guest passes are allocated to users when they purchase certain products. The friend can then play the game for a limited time. Once the guest pass expires, they will be prompted to purchase the game in order to continue playing. A guest pass is an easy way to let your friends try out your favorite games with no commitment or expense on their part.   

Pretty clever idea. 
 
I will post my steamid and notify whenever I want/am offering a guest pass. 
 
perplexedmind 
 
(I don't want killing floor, thanks)

My SteamID is Matrix9455 (search for it in the community section, I don't know my legit account name off the top of my head and am too lazy to look for it). 
 
No killing floor for me, thanks though.