Google Maps Mobile (for your cellphone) can now approximate your location on a non-GPS type cellphone. It does this by using your current cellphone tower location. I tried this on my Blackberry, and it seems to work (at least while I am at the office; haven’t tried it elsewhere).

You get a blue dot on your Google Mobile Map that shows your approximate location. More information on the Google Maps Mobile blog here: http://googlemobile.blogspot.com/2007/11/new-magical-blue-circle-on-your-map.html . Note that this is version 2 and beta, and you may want to read the comments on that blog, as some people are reporting problems (as others report success). But the concept and implementation are quite interesting.

A short video is on the site explaining how it works.