I own a K2CNC KG-3925-G CNC Router and I really would like to do probing of 3D Surfaces. I make Guitars and do 3D Engraving and this would be of tremendous value to me. Anyway after surfing around for awhile I found the TP-100 3D Touch Probe and it looks like a winner to me. It's the perfect size to fit my machine's limited 5" Z axis travel. You can see more info here:

http://www.cadcamcadcam.com/index.asp?PageAction=VIEWPROD&ProdID=10