One of the nice things about digital distribution is that games never run out of stock, so you can do your Christmas shopping in your robe and slippers at the last minute. Valve seems to be counting on that perk, because it's kicked off a gigantic holiday sale on Steam. The sale runs through January 3 and covers huge chunks of the distribution service's catalog.
The juiciest offers seem to be publisher- or studio-centric packs. For instance, the id Super Pack includes all id games (as far as we can tell) for $34.99. The Eidos Collector Pack includes Batman: Arkham Asylum, three Hitman titles, a couple of the most recent Tomb Raider games, the two Deus Ex games, Thief: Deadly Shadow, and many more, all for $49.99.
There are even fresh titles to be had individually at a discount. Borderlands is on sale for just $33.49, Batman: Arkham Asylum goes for $33.40 on its own, Operation Flashpoint: Dragon Rising sells for $19.99, and the slightly older Mirror's Edge can be nabbed for a scant $4.99.