Snip...
Probably more than I can remember. There was a thread on that in the past.
In some order: Steppenwolf, Grand Funk, Bloodrock, Chicago, ELP, Yes, Humble Pie, King Crimson, Gentle Giant, McKendree Spring, Dr. John, Larry Coryell, Siegal-Schwall Band, Allman Bros, Marshall Tucker, Charlie Daniels, Mac Davis, ZZ Top, Blue Oyster Cult, Eric Clapton, George Harrison, Jefferson Starship, Earl Scruggs, Kiss, Grinder's Switch, Golden Earring, Thin Lizzy, Roy Buchanan, BB King, REO Speedwagon, Bob Seger, Led Zeppelin, Jethro Tull, Pink Floyd, Frank Zappa, Aerosmith, Foghat, The Outlaws, Bob Dylan, Steve Winwood, Peter Gabriel, Don Henley, John Hartford, Brewer and Shipley, Billy Cobham, Paul McCartney, Al DiMeola, Jean-Luc Ponty, Stanley Clarke, Eric Johnson, Steve Vai, Loudon Wainwright, Jr. Brown, Steve Miller, Jimmy Buffett, Toby Keith, James Taylor, John McLaughlin, Johnny Winter, Robert Earl Keen, Townes Van Zandt, Guy Clark, John Prine, Kenny Chesney, Sugarland, Pat Brown, Dierks Bentley, [-]Taylor Swift[/-], Kansas, America, Jerry Jeff Walker, Ray Wylie Hubbard, Dweezil Zappa, Jackson Browne, Steely Dan, Return To Forever...
Probably left out some/many?