In what may be its finest promotion yet, the latest Humble Indie Bundle kicked off today with five highly rated indie games for less than the price of one. In case you're unfamiliar with the formula, the service lets you set your own price for the titles involved. Pay less than the average rate (currently $7.38 and rising) and you'll get Amnesia: The Dark Descent, Psychonauts, Limbo and Superbrothers: Sword & Sworcery EP. Pay more than the average price, and you'll get Bastion as well.

All five games work on Windows, Mac and Linux with modest requirements that should play nice with most modern machines (Amnesia: The Dark Descent might not run well on integrated graphics or very low-end cards). Bastion, Limbo, Sword & Sworcery, and Amnesia were considered some of last year's best games -- indie or otherwise -- with average review ratings in the mid to high 80s. Psychonauts dates back to 2005 and despite its relatively poor sales, it also has very high ratings:

You'll have to spend more than $1 if you want at Steam key and paying less than that doesn't leave the organization much profit after transaction fees anyway. Your payment can be split anyway you want between the event organizers, the developers and charities including the EFF and Child's Play. So far, 145,000 gamers have spent over a million bucks (with 14 days to go!) and the highest submission is $3,000. Windows users have spent an average of $6.81, $8.87 for Mac and $11.39 for Linux.