John Mayer, Jason Mraz, Stevie Ray Vaughan, Matchbox Twenty, Ben Harper, Jack Johnson... those the most but also:
Pearl Jam, Neil Young, Jimi Hendrix, Norah Jones, Coldplay, John Butler Trio, Santana, Travis, Michelle Branch, Eric Clapton, Creed, James Taylor, Eagle Eye Cherry, Living End, Foo Fighters, Good Charlotte, The Eagles.
... and I'll stop.