I am going to be visiting Northern California shortly. I am trying
> to find out what carriers have GSM coverage in 95437 Fort Bragg
> California. Is there a database that might be able to help?
The two major GSM carriers in the US, Cingular (now including what used to be AT&T Wireless) and T-Mobile both have 1900MHz band licenses in Mendocino. If you visit Cingular's web site, you can find a coverage map with a little blob around Fort Bragg, so assuming you have a 1900MHz phone, it should work. T-Mobile has no coverage at all in Mendocino, and the 800 MHz band carriers, US Cellular and Verizon, are both CDMA.
The Mendocino coast is so hilly that I'd expect plenty of dead spots even for carriers that do cover the area. But it's very pretty.
R's,
John