NetWorldMap
NetWorldMap provides free geolocation utilities.
http://www.networldmap.com/

Akamai - EdgeScape
EdgeScape is Akamai's Geotracking solution. Not much information is available on the site itself for this service but a white paper is downloadable after registering.
http://www.akamai.com/html/en/misc/cd_whitepaper.html

Digital Envoy - NetAcuity
NetAcuity provides geolocation services. API available for C, Perl, and Java.
http://www.digitalenvoy.net/

InfoSplit - Net Locator
InfoSplit offers Java classes or ActiveX components ready to be integrated in your application to use their geolocation services. The Flash site provides an online demo of their capability by attempting to show where you are connecting from.
http://www.infosplit.com

NetGeo - AcuProfile
NetGeo's geolocation services.
http://www.netgeo.com

Quova - Geopoint
Quova's geolocation service.
http://www.quova.com/