It's part of what the Humble Store is calling the Indie Showcase and it's awesome. Particularly if you like paying low prices for those cooler than cool Indie games. Finally, a chance to play all those games we've been pretending we've already played.
Here is a list of games that currently cost less than what I'm planning to pay for my lunch...
— Gone Home — Retro City Rampage — To The Moon — Cave Story — Proteus — Little Inferno
That's just the tip of the iceberg. There's almost 50 indie games on-sale and the majority of them have fairly massive discounts I'll probably be buying a few.