how can i find out someone's ISP from their IP?

[gplanet]

I have someone's IP what would be the easiest way to find out information about their ISP? There's some abuse I want to report

 

[BooneRebel]

ping -a should give you the registered name associated with the IP (which will probably something like router-port.domain.com)

 

[Talon]

http://www.arin.net/whois/