what info can you find out by knowing an IP, how and what tools/ sites are needed for this?

I put up a site and saving all the IP addresses of users is add开发者_Python百科ing some overhead. I am trying to figure of this benefit is justified.

I never used an IP address for anything other than correlating user activity for trending and site usage metrics.

I know the IP information can be used to audit and trace things back to the user of that IP.

what exactly is the info you can gather that would be useful based sole on the IP address and how can i get this info?

If the user is a criminal you can report them to the FBI. Trying to block an attacker based on IP address is really short sighted. Proxy servers are free, ip addresses are pennies.

There are lots of services that can identify the ISP and/or geographic location for the IP addresses. Lots of website analytics providers (e.g. Google Analytics) use this method to give you stats about the geographic location of your users.