Microsoft Location Finder
 

Microsoft Location Finder is a client-side application that turns a regular WiFi enabled laptop, Tablet or PC into a location determining device without the addition of any separate hardware. When launched by a user, Microsoft Location Finder uses WiFi access points - or reverse IP lookup when WiFi is not available - to center and display the person's location on a Windows Live Local, enabling the user to quickly and easily search in their present location.

Download it here.