Ritchey WCS True Grips
These grips aren't for everyone. However, if you're looking for the absolute lightest grip possible, the WCS True Grip might be for you. Made out of durable neoprene foam that's lightly textured for added grip (think a souped up version of the foam grips on an old 10-speed) about the only frill offered is Ritchey's signature hexagonal shape for a splash of comfort.
I like the larger diameter and shock absorbing foam material of these grips. Only problem is durability, but they are pretty inexpensive. Buy 2 pair.