I briefly touched on Harvard's Third Side Project a while back.
3S truly is worth an in-depth look.
Perhaps meant more for the consumer than the professional neutral, this website is nevertheless a wonderful resource.
Take a poke around the awesome 3S website and even download some free wallet cards or a Third Side One Day Workshop (Download Facilitator's Guidebook / Download Participant's Guide).
Or perhaps try 3S tools.
Or even watch a video of William Ury addressing a conference on the role of The Third Side.
"The Third Side is a way of looking at the conflicts around us
from the larger perspective of the surrounding community"