Measurement tools in MoI would be nice.

I use this tool a lot on all my graphics programs:

http://iconico.com/caliper/

It has a nice feature where you can calibrate to custom units. For example, you draw a line that should be 5mm long. Adjust the caliper to match the line and set it to read 5. Now other geometry can be measured directly in mm.

This tool is also nice for measuring lines positioned at an angle (grab the caliper and it rotates).

Ed