After having it on my site for over a year, I have exposed the GrabIP API (I can’t believe I have a something I can even call an API) for random IP Address checks. Simply send a request to the system in the following format, and it will tell you which IP Block it resides in.
http://www.pierzchala.com/grabip/request.php?[INSERT VALID IP ADDRESS HERE]
The database is not as precise as some of the other ones that are available, but it was never designed as a tool of precision. I wanted a way to determine where visitors to my site were coming from, and I didn’t need the level of detail available in some of the for-fee IP lookup databases.
A somewhat outdated write-up on the GrabIP system is available here.
I will be exposing the GrabIT2 API soon.