There's a commercial company called Zoomsafer that has been doing work related to this. Their current software offerings focus on measuring use of devices in fleet contexts to help companies manage risk.

You could use the TAPR Open Hardware License:

http://www.tapr.org/OHL

It's a copyleft-style license drafted by a lawyer that permits a broad range of activity. Bruce Perens and Eric S. Raymond helped review it. Open hardware licenses are still in the early stages of evolution and adoption. If TAPR does not meet your needs, the Wikipedia entry on Open-source hardware lists more alternatives:

http://en.wikipedia.org/wiki/Open-source_hardware

Taskjitsu could work for you. This professional services automation package tracks customers, projects, tasks, and time, and has extensive reporting features. It's an open source Java application distributed under the GPL.

It might be particularly useful to you if you want to track time spent per job. You would create a separate Taskjitsu project for each job, then log time per project in the time sheet system.

It runs under Tomcat 5.0 on a variety of different operating systems.

My company, PKR Internet, provides commercial support for Taskjitsu. Taskjitsu's motto is "The Art and Science of Tasks and Time".