I do this and use the company/site name as the user name. Also, if I have to fill out a form anywhere I put the company name in the Address 2 line (or any unused space). This allows me to track where my information goes. When I get something from Company B containing Company A's name I know the flow of my data. I haven't figured out how to use this to my advantage but it is interesting to see.

That's the second person that came to mind for me. The first was my father.