Hey, that Leo Kottke track is quite a favourite of mine too, Plankton! My fave Kottke album is Greenhouse though.
And dwill, your post is right on topic. If the OP guy is still around, he should be pretty pleased with your suggestion.

Ronnie Earl's Healing Time album (2006) scores for being instrumental throughout, but he muddies the waters, ahem, with some jazz and some organ accompaniment:-

The Rolling Stones did a few songs of Slim Harpo.

Slim Harpo - Dynamite

On their only easy-to-find album, Psychedelic Guitar Circus are too eclectic to be in this thread, but there's another recording, of a concert in Aug '93, where they did a few blues numbers. First up, a delicate-then-burning version of that Peter Green standard, Jumping At Shadows:-



This blues jam, hidden away in some obscure corner of YouTube, has only received 362 views in 7 years:-



This live album seems pretty obscure, so here's a pic of the cover, just to prove that it exists:-

http://4.bp.blogspot.com/_YQBsfGwVEe.../s400/psy1.jpg