Interested in working with identifying where an IP originates from geographically? Maybe for your website (you could localise the display or whatever) or maybe for your applications? Actually I heard about this in connection to how the Conficker worm/virus works, Conficker actually use this database to orient itself, yeah I know it’s a crazy world out there 😉
Both a free and a payable version is available, I haven’t looked into the API yet – but if you are into web development then this is not likely to ruin your day.