Watch the Lead Or Rhythm online guitar lesson by Corey Congilio from Rhythm Factory: Texas Blues
About once a course, I throw in a self indulgent yet pertinent example. I've heard countless players use this riff for rhythm or lead playing. The most recent was Jimmie Vaughan. Check out his recording Strange Pleasure. He released this record shortly after Stevie's death and there is some great stuff on it. This example is out of G minor pentatonic and works nicely over the shuffle. Put this one in your repertoire ASAP!