How about Big Joe Williams? He's a bit unique in that he played a 9-string guitar (that he improvised himself), and he had all kinds of great bass runs that you just won't hear elswhere.
Also, Brownie McGhee (with Sonny Terry) are considered by many to be the standard for guitar/harmonica duos.
Also, Brownie McGhee (with Sonny Terry) are considered by many to be the standard for guitar/harmonica duos.