Freegames??

I take them (?)

Plenty of them here: http://store.steampowered.com/genre/Free%20to%20Play/
Hmm, doesn't seem to link well. Guess that's from the spacing.

Cool story bro!

There are hundreds of them right here

Besides that, you've got a ton of great games you haven't even played on your account... o_O

There are no such deals happening right now, though if you want to know about any, be active in these forums so you can see topics about them before the scummy traders get most of the keys.

Karate Chop!

Stop it Spongebob! I'm not in the mood for spanking right now

Portal 2 was free a while back on code.org. In fact, just lurking the forums around here is pretty useful, as people tend to point out when something is free, like the gazillion Enclave keys from a while back, or the GMG thing, or whatever.

Some of the games on GOG are free, and all of them are worth getting.

(Yes, GOG is awesome.)

Rockstar handed out free copies of Midnight club 2
Popcap handed out free copies of Peggle
And there were free copies of Crayon Physics Deluxe as well
I've missed them all :'( But luckely L4D2 was free as well, and I got that, which is nice.
Try to look for free bundles on google, and keep an eye out here.

http://www.thefreebundle.com/

Mafia 2 and Civ5 GMG

Encalve was free

Anomaly Warzone Earth was 10 000 free keys from BundleStar!

Portal 2 code.org

And L4D2 on cristmas...

Thats all what i get for free last year... =^.^=

I remember there was a thread about this a while ago: clicky

I don't believe there's any deals like those currently active, however I'm always happy when I see someone else has posted announcements about them...
But it's a whole other thing when I find out I was too late.