Anyone used MaxMind Geolocation library? Have alternate suggestions?

I'm looking for a (fast) way to tell the region/city of an IP address and came across MaxMind Geolocation http://maxmind.com .

They have a free version and a commercial version. I was wondering if anyone had used it, or had alternative suggestions.

One interesting thing is that they require that you install some C library to query a downloadable binary which contains the IP block data. They also provide APIs in all the popular languages. The queries seem fast...looks like you can look up ~hundreds per second which is what I need...