So they put the Humble Indie Bundle 2, inside the Humble Indie Bundle 3 so you can get more games, while you buy games. For those that don't speak expired-meme, this essentially means that if you buy the latest Humble Indie Bundle, you can get the games in the Humble Indie Bundle 2 for free.
There's only one catch - since the Humble Indie Bundle allows you to essentially pay what you want - to receive the Humble Indie Bundle 2 games, you must pay more than what the average user has been paying up to now. At the moment that means paying at least $5.
But it's barely a catch - the Humble Indie Bundle scheme actually donates money to good causes, in addition to providing gamers with great games at a great cost, in addition to spreading the word abot under appreciated Indie games. Really you can't lose here.
Pay, say $10 - or less if you want - and you can get the following...
-Crayon Physics Deluxe -Cogs -VVVVVV -Hammerfight -And Yet It Moves -Braid -Cortex Command -Machinarium -Osmos -Revenge of the Titans
Yeah - that's good value.