FGdb is where lots of data about Free Geek is kept, including such things as volunteer names and hours, gizmo types and flow, dollar amounts of donations we've received, and much more. It is comprised of a PostgreSQL database and a Ruby front end.
You can access it through a web browser, provided you're inside the Free Geek building (not including the wireless network.) Just type the word data in the address bar (you know, where you'd usually type a big long URL like http://www.example.com.)
If you want to find information that isn't available through the web page, and are familiar with (or willing to learn) SQL, check out FGdb SQL queries for some suggestions.
Problem with the database? Create a technocrats ticket in RT. Screenshots are helpful.