A simple Perl wrapper around the Google Maps API. It allows you to easily create maps with markers, polylines and information windows. You can now look up locations around the world without having to install a local database.
Geolocating your users can create a better experience, but it can also be used in devious ways. For example, cathysteeth.com claims to have a cosmetic dentistry solution discovered by a mom. And wouldn't you know it, Cathy lives in your home town. And your home town.