Hi Liz,
If you check out Deb Ng's freelance writing site (
Freelance Writing Jobs), look under Writing Job Leads (bar at the top of the page). She often breaks down the jobs according to category, including Technical. This way, you can scan right to the jobs you're best suited for and most interested in.
Also, try looking in the current Writers Market -- they list all kinds of publications, such as trade magazines that aren't as mainstream but perfect for a particular niche.