The blues recorded in the 20s and 30s is what really turns me on - a good place to sample a lot of that is on the Weenie Juke:

http://www.weeniecampbell.com/juke

Takes requests, too.

I guess if I had to pick one favorite blues musician, it'd be Blind Lemon Jefferson... but there are a lot of guys who maybe only recorded a handful of songs each - those are often among my favorites, too. Lots to explore!