Adapt a digital caliper for checking bed level on the UIltimaker.

I used this device:
LCD Digital Tread Depth Gauge Gage Inch Metric 0.0005 Tire Thread Electronic ($4.95) http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=350809115884

Drill out the bolt holes with a 6mm drill because the plastic bits make it very tight.

The digital depth gauge drops into this holder, and the extender fits over depth bar to reach the print bed.

The depth gauge sits lightly in the holder so that it can be removed during printing.

Pull the rod up while manually moving the print head to different areas of the bed, then push the rod back down and adjust the bed height level screws accordingly.