A dear friend of mine has picked up her son's "student guitar" and is learning to play. She asked me to preview this site she found: The On-Line Guitar Community. I checked it out. It uses tab and play back to teach guitar techniques as well as songs. There are a few blues songs on the site at this time. It also has a "Groove Builder" that allows you to set up chord progressions with which you can then play along. I set up a basic chord progression in the key of C for my friend. I'll let you know if it works for her.
It is free to become a member (of course you end up on some "list" I'm sure). You can then submit "lessons" to the site.
Might be a place to put in some new folk "lessons". All of you Mudcat guitar players can check it out and let everyone know what you think.
Roger in Baltimore