I just ran across this on E bay. For those who would like an accurate measurement on your Z axis this would make a good accessory. Available in 6,8,12,18 and 24” lengths. Also a larger remote display if you need that($70).
A lot of times I like to confirm the depth of my cuts and this seems like I could do that in real time without having to stop and measure with a caliper.
http://www.ebay.com/itm/8-200mm-VERT...item518ce17f5e