There is new FireFox extension that support GeoLocation. GeoLocateFox put a little icon (grey globe) in the lower right hand side of your firefox browser window. The globe activates when you visit a site that supports GeoLocation (such as this one) When you put your mouse over the icon you get a little map like the one below.
One interesting note about this extension is that is only supports Yahoo! Maps. Here is the explaination from the author.