I've learned about some great music from this thread. Thanks to all. I'm going to mention a few already covered by others-maybe I'll be a bit more specific.
Slide Guitar....
Old Slide
Elmore James-The boxed set "Elmore James King of the Slide Guitar" is required for any blues rock fan. A listen will show how influential James was. ZZ-Top pays homage with every song.
New Slide
Dave Hole-"Short Fuse Blues" and "Steel on Steel" are each fantastic. BTW-Hole is either Aussie or British I can't recall which.
"Straight Guitar"
Blues-Rock Current
Gov't. Mule-"Dose" it's brilliant AND beautifully recorded.
Chris Duarte-"Love is Greater Than Me" and especially "Texas Sugar/Strat Majik" are great. IMO-Duarte would be an SRVesque superstar if not for his heroin problems.
The Gales Bros. Left Hand Band-"House of Blues" is required. As Mojoman mentioned it will not be easy to find-it will be worth the effort. Total greatness.
Jimmy Vaughn-"Do You Get the Blues". He ain't SRV and he does not try to be. Excellent album.
George Thorogood-"Greatest Hits"
Blues Rock Older
Canned Heat-"Best of Canned Heat" the digitally remastered version is required.
Little Feat-I like most everything LF recorded but the song "Dixie Chicken" is sublime.
Real Blues that Rocks
Albert Colins-"Cold Snap".......if you don't like the AC song "I ain't drunk I'm just drink-in'" you are nuts.
Buddy Guy:
1. "Buddy Guy-Damn Right I've Got the Blues"
2. "Buddy Guy-Stone Crazy"
3. "Stone Free-A Tribute to Jimi Hendrix" most of this album is crap, however, Buddy Guy does a version of "Red House" that is, IMO, better than Jimi's.
Older and really old blues that is interesting:
"The London Howlin' Wolf Sessions" Wolf died not long after this recording...he sounds great with Clapton, Winwood, Wyman and Watts.
"The Very Best of John Lee Hooker" enough said.
Really old:.......old to oldest: (no Texan deserves the title if he does not know these well-everyone else should too)
Leadbelly-more "negro-folk" music than blues but still great.
Robert Johnson's boxed set...it is great. If not for Johnson where would "The Grateful Dead" have gotten their best material?
Blind Lemon Jefferson-"Moanin' All Over" it's from the 1920's so the audio will not win any awards but you should own a copy. BLJ influenced RJ etc. etc.