ORIGINAL: itileman

I have these and they are great: www.coloradochaps.com

They're kevlar with knee/shin protection pads and leather panels at the calves to keep them from melting on the pipes.
They hook to your belt rather than have the waistline set-up. Top quality gear made in the USA.

I also have oilskin chaps that I use for upland bird hunting. I don't see them holding up real well on a motorcycle, plus they get stiffer than a board when it's cold. They're not cheap, either.