Rarely do I effusively recommend a bundle made up entirely of games I already own, but it's kinda hard to argue with every BioShock, Spec Ops: The Line, Mafia II, The Darkness II, and XCOM: Enemy Unknown, among others. The Humble 2K Bundle does come with a slight catch (a flat rate of $20 if you want a couple of the more recent games), but even then it's a formidable deal. Unfortunately, this will technically count as purchasing The Bureau: XCOM Declassified, but don't worry: I won't tell anyone.
If you pay below the average, you're guaranteed BioShock, The Bureau: XCOM Declassified, and The Darkness II. You can, speaking in the mighty thoughtrealm of theoreticals, get those for a penny.
Bust through the average and you can top your haul with BioShock 2, Mafia II, Spec Ops: The Line, and "more games" at a future date. Paying $20 straight out the gate, meanwhile, gets you XCOM: Enemy Unknown and BioShock Infinite on top of all that.
Of course, many of you probably also have most, if not all, of these games. Still though, I don't know. It might make a solid gift for your less gamerly friends or something. And as ever, you can just pour all of your nickels, dimes, sporgs, and wurzywots into charity if you want, for that is the Humble way.
Are you buying, or does this bundle suffer from greatest hits collection syndrome? Is it redundant for you if you've already been playing 2K's big releases for the past 2,000 years?