The summer is almost over but there is still time for one of Valve's seasonal Steam sales! CVG UK has dug up a post on the Steam Powered forums by Mike Blaszczak that confirms that another summer sale is in the works
We are planning a sale sometime this summer. Hope that helps!
There are also sites reporting that this years bundle list has been leaked.
"Now, if a unicorn can regenerate magic faster than the headcrab can suck...
We could have a super headcrab epidemic on our hands." -EatChildren