I don't know whether to thank them or curse them. With 2 kids, both having their own computers (11 & 19), I find myself spending money on games at an insane rate when Steam holds their crazy sales.... they just started their "Summer Sale" - and I've already spent a hundred bucks or so on games (of course, that's for something like 50 new games between us all).
If you want to be bankrupted by them, check out this site: steamgamesales.com.
I'd recommend Borderlands GOTY edition to anybody who doesn't have it yet. Lots of great stuff at insanely cheap prices. Of course, this is all PC games... the advice on SlickDeals is to buy Daily Deals (front store page) and hold off on regular sale items, since it's going to run until July 10, and some games might get even cheaper.
Also, another deal on GamersGate/UK... Civ V for $11.18 (after currency exchange, that's what PayPal charged to me). You can register the serial number on Steam to activate the game there.
Just don't come crying to me when you wake up in a few days after a marathon PC gaming session with an empty wallet. You've been warned.