The new Opera "technology preview" includes the W3C's Geolocation API, a way for websites to request your physical location - and for you to give it. If you think that's a good idea.
The idea is that web apps will use this API spec to provide you information specific to your particular place on the planet. A restaurant review site could instantly serve up a list of nearby coffee shops. A weather site could provide the local forecast.
This fall, mozilla rolled the API into a firefox add-on dubbed Geode, and it's now part of the new Firefox 3.1 beta, released earlier this month.
Like Mozilla's, Opera's API taps into a positioning system from an outfit called Skyhook Wireless. Skyhook's Loki service maps your location using Gps, WiFi signals, or cell phone towers.