There's an interesting article on the ABC News website about the knowledge which has come from the first 6 years of the Cassini mission to Saturn:
Scientists now say the serene and majestic rings of Saturn are actually a rough and violent mix of frozen particles
Although now known to be mostly water ice, apparently the rings contain a mysterious reddish contaminant which "could be rust or small organic molecules similar to those found in red vegetables." Standby for the crackpot theories!