I'm not sure how long the link will be live, but Wolfgang's Vault is my favorite web site this week. It looks like a group purchased the original recordings of "Bill Graham Presents" and "King Biscuit Flower Hour" and then put the recordings online for free. Right now they have several hundred audio recordings of live concerts dating back to the late sixties. So far, everything I've heard has excellent sound quality, and the performances are really stinkin' good. I've been getting my 'funk' on this morning with Stevie Wonder and Sly and the Family Stone.
I'm guessing the Intellectual Property Nazis will take the service down at some point in the future. But as of today, it is rockin'.