The Destination Out blog has a nice post about Sam Rivers, including three trio tracks from his 1975 album Hues. As a teenager in the 70's, I visited my local record store and bought Rivers' Involution, which was part of the Blue Note Reissue Series. That record and Andrew Hill's One For One, also part of the series, just blew me away. As much as I liked Dexter Gordon and John Coltrane, the intensity of Rivers' tone and his compositions just reached me like no other tenor player. The fact that he wrote his own exercises also appealed to me.
I had a chance to see him with the University of North Texas big band about 6-7 years ago and they did a great job with his charts. As Destination Out states, Sam Rivers should be much better known than he is.