Propellerhead Software has released Dr. Octo Rex Guitar Collection, a free ReFill with guitar loops for Reason 5. The ReFill contains 355 acoustic and electric guitar loops with different chords in 10 styles.
With the chords composers can make rock songs, but of course the loops are also good for creative usage. The loops are available in rex format for the new Dr. Octo Rex player. This video gives an impression of the possibilities of this ReFill: