HostIP.info API

This is an easy HTTP oriented API to locate IP addresses and Geocode them. If you don't supply the "?ip=aa.bb.cc.dd" bit, then the ip address lookup of the calling machine will be located instead (here, the aa,bb,cc,dd are decimal digits). If you add &position=true to the end of the URL then latitude and longitude will be returned also. Both HTML and XML formats are supplied for your convenience.
More information: http://www.hostip.info/use.html