These turns up with PEAR and PECL:
PEAR :: Search: geo
PECL :: Package Search
As mentioned, the results are not necessarily accurate (some are known false results). Say, my company owns an AS and have a range of IPs allocated, that are assigned to locations at different parts of the world. Of course, if you look at netblock owner the location will be that of our company headquarters, but that does not represent the location of our servers which really got assigned those IPs. To date, I have yet to see a geolocation service or package that guesses the locations of those offshore servers right.
So, don't treat these kind of geolocation data too seriously. It will be good for, say, selecting a default language for a multi-lingual site based on an estimated location (that the user can still switch if the guess is wrong). Don't expect you will find a source, no matter how much you are willing to pay, that gives you "accurate" results, let alone zero false results.