Humble Weekly Bundle is music games. Symphony, Sequence, and Bit.Trip Runner, plus Audiosurf, Beat Hazard Ultra, and Retro/Grade if you beat the average.
I already have Sequence and it's so insane it stresses me out. You have to manage three separate windows with falling arrows that you have to hit to either heal yourself, gain mana, or protect yourself against attacks. You can cast spells to attack, but you have to hit their key sequences perfectly or they fail. It's seriously difficult, but a good challenge if you like rhythm games.
I haven't played Symphony yet but it looks awesome. A very clean-looking shooter generated based on your music files. I'll be trying this in a bit.
I think everyone knows about Bit.Trip Runner already. Run, jump, avoid hazards, collect gold. I have Runner 2, and I'm looking forward to trying out its predecessor, although it looks even more difficult.
I have Audiosurf already, Beat Hazard looks too chaotic for me, and Retro/Grade doesn't really interest me, so I won't be beating the average.
The current main Humble Bundle is eBooks again, which got me excited until I saw which books. Most of them don't look terribly interesting this time around, with the notable exception of Zombies vs. Unicorns. So I guess that's worth a dollar.