L4D2 is awesome deal at that price. Anyone looking to play an awesome zombie shooter, should get it. :)

And get Zeno Clash at $3.75. Get it NOW!

Haven't you missed the mega cheapness sale on them now?
Personally I hit a point I couldn't progress beyond in Overlord 2 which was clearly some kind of game breaking bug as the solution was fairly obvious. No such problems with Overlord 1 and it's still prettyful enough too.

Even as a purely single player game L4D2 is worth it at the $7ish you can buy it in a pack.

How much did they go for? I missed the first and second day of the special promos.

I can't remember now. But I think it was roughly half what they're currently going for.

Snap, didn't even know it was on a special promo. Maybe I'll just get Overlord 1...

Well, here's what I've found of most interesting regarding prices, apart from the 24h deals:
Introversion Complete Pack $5
Ubisoft WWII Collection $33.49 (Don't be stupid of buying the Brothers in Arms Pack, which is $33.47; instead buy this ubi collection with 6 more games for an extra 02 cents!!!11!) Psssssh, and don't tell steam about this.
Call of Duty Pack $29.99 (Bobby Kottick either got a flu and is sick to finally discount this, or it's only discounted to promote the franchise and its future plans)
The Stronghold Collection $22.49 (you can also buy this at retail, the discs are drm-free)
NovaLogic Everything Pack $34.99 (If you played the games back in the day, you know you'll end up buying it)
The Witcher $6.79
Red Orchestra: Ostfront 41-45 $4.99
Chrome + SpecForce Bundle $1.99
Time Gentlemen, Please + BTDT $2.49
Indigo Prophecy $3.39
Cryostasis, King's Bounty: The Legend, Men of War, NecroVision $3.24 each
And obviously, both the THQ pack and Eidos pack. id Super Pack is nice too, but it got discounted to approximately $25 back in holiday, currently it's $34.99.

The expansion really doesn't add anything interesting to Overlord 1 -- it's a few new small areas and items that are largely pointless given the game's difficulty level. I've yet to play Overlord 2 more than a couple of hours having bought the pack for $8ish almost a year ago and not really having the time to pick it up again.

my trying not to buy anything failed as soon as i saw how cheap Zeno Clash was...

Haha it's exactly the same for me.
I'm still hoping they'll have a specific sale for one of the decent RPGs I don't own yet though (or that I owned until someone "borrowed" them).

What is it with these Steam sales? I know Force Unleashed has a story that can only be described as bollocks yet my instinct says Star Wars + Cheap = Click. *sigh*

Me too, Zeno Clash is the first thing I've bought from this sale, as I'm only buying the 24h specials for now...
I thought it would be a giant sale again, but as you dig the catalog you see that half of the games aren't discounted, and the other half is a bit overpriced (+$1, $2 or $3 more per game compared to the holiday sale).
Still, there's a whole week of 24h specials to come, so I'll keep checking that list. ;)

Lower prices let you overlook things more easily.
And TFU (for the PSP) wasn't that bad. Cliche plot that was chock full of retcons, but whatever.