Jet City Blues
Check out Mike Lynch's Harp Blues Blog. Some good stuff there. Jet City Blues I liked his tip on amp channel jumping. I've used it, and it does make you a lot louder, and not having to struggle with volume helps your tone.
I cleaned up my tab for Sonny Boy's Help Me and made it into a short book. There's a Kindle version for 99 cents, and if you buy the paperback you get the Kindle free.
Playing "Help-Me" In the Style of Sonny Boy Williamson II: A step by step, note for note analysis of some of Sonny Boy's Signature Riffs