I just got another great resource! Take a look here:
Niles Hokkanen's catalog
Scroll down to the back issues of the Mandocrucian Digest. Look at the descriptions on issues 9-12. An interview with a blues legend, a Rich D blues article, 3 J McGann articles on blues (I probably should have ordered #13 to make it 4 articles), some of Nile's rhythm articles that are very applicable to blues (shuffles and walking chords), a couple of the bluegrass articles have a definite blues bent to them and the Cajun shuffle has some application as well. As an added bonus, you get pictures of John McGann with hair - lots of it! #
In another thread, Niles recommended his book on Bluegrass Up the Neck as a good resource for blues technique also (that's available on the same page). The articles are perfect for my short attention span, though. It's not going off in yet another different direction; just short diversions that apply to what I am trying to learn in general. Good stuff - this moves to the top of my previous list of blues resources (none of which are a comprehensive standalone blues course; such a thing doesn't seem to exist)!
"First you master your instrument, then you master the music, then you forget about all that ... and just play"
Charlie "Bird" Parker