Google Analytics > Visitors > Network Properties > Network Location. This tells you which ISPs your visitors came from. And it turns out that most businesses own their IP addresses.
I guess it's as simple as that. If you google: what is my ip, they'll show it to you. Then you can use a site like webyield.net to resolve that to a domain name, our just use
nslookup yourIp in your dos console. Once you know the domain of your visitor (in this case, you), if they're a company, you can bet that www.theDomain.com will be a website that will contain their contact information.
But be warned, in case you want to use this info to limit the access to an AWS machine via security group to only allow inbound from your IP. The result you get from googling "what is my IP" is not necessarily the IP that amazon will see. In my case, "what is my IP" yeilds X and I only allow 22 to my EC2 box from X, and that is successful, but when I additionally install httpd on that same box and only allow 80 from X, I fail to connect. Allowing 80 from all and grants access and checking /etc/httpd/logs/access_log shows my client IP as Y. Sure enough webyield.net shows that Y is another box owned by my internet provider, so I conclude that sometimes I appear to the world as X and sometimes I appear to the world as Y.