http://www.scrublade.com/

They have an interesting design that has two blades, each has a leading edge that has scrubbers to get rid of mud, dirt, and bugs, then a trailing edge that squeegees it.

They've been working well for me so far... http://www.sierraexpeditions.com sells them for $18 each (for the 22" versions).
Figured I'd share a cool product that seems to be working well for me so far. I've got them on the fronts, and just got in a new one for the rear.