Eric Clapton

started his Crossroads Guitar Festival to support the Crossroads Centre, a treatment center for drug and alcohol addiction. From Clapton's site:

The second Crossroads Guitar Festival took place July 28, 2007 at Toyota Park in Chicago. The day-long festival featured music collaborations from Eric Clapton, Steve Winwood, BB King, Willie Nelson, Jeff Beck, Vince Gill, Sheryl Crow, Buddy Guy, John Mayer and many more!

Here's Sonny Landreth from the 2007 Festival. (guest blogged by Steve Audio)