MiniGPS is a nice little tool for the Series 60 phones, that is able to tell which phone network node you’re connected to, and fires events accordingly.
For example if I’m at University I can tell the phone to switch to silent whenever I connect to the local node, and to go back to normal when I’m out.
In fact, the University campus is covered by at least three nodes. Fortunately MiniGPS lets you create groups, and have the events fired upon entry or exit of one of the group nodes.
At the moment I’ve programmed the phone to go silent whenever I am on University campus, switch to a subtle ringtone when I’m at home, and have a very loud ringtone when I’m on the M27 motorway.
You can also do a few other things: set the background image, show an alert box, or send an SMS.
I’d quite like to see a cheaper notification method though. It’d be nice to be able to ping a website somewhere with GPRS. That would allow those of us inclined to do so to get our blogs to say "I’m in Southampton" (or more serious work-based locating) – it at least opens the possibilities up a little.
Simon Kittle has also found some mobile locating tools, although they are all pull-based (ie. website polls phone networks on request) rather than push.
MiniGPS has a 21 day trial, and costs 14.95 EUR