We use the GeoIP database from MaxMind for many things:
- OpenX Ad server geotargeting
- Custom (Home grown) GeoIP plugin to show cities and countries under IP address in Who's Online (online.php) to admins and mods
- Custom (Home grown) GeoIP plugin to show cities and countries in welcome message to all members in Navbar
- Custom (Home grown) GeoIP with Bayesian classifier plugin used for spam classification and moderation.
- Custom logging (with added GeoIP info in log files)
- More, can't remember.
Should be a standard part of vB the same as it is with OpenX ad server. You can do a lot with geo information.
Other vB mods that use other methods are not very scaleable (or accurate) compared to using the binary database (free) from MaxMind.