"Picking On" tribute albums

I have a "Picking On the Rolling Stones" CD that is awsome. I've seen a couple of others out there for different artists as well. I've Googled around looking for the muscicians site but cannot come up with it. Are all these done by one group/artist, or are they different? Anyone have a list or website that lists all the artists they have "picked on"? I'd love to get a couple more.
Thanks in advance, John