First of all, the Joomla Visitor Map module is AWESOME!

The only thing that it is missing- is that the viewer would be able to click on the pins on the map to view registered user's Community Builder profile.

Any thoughts on how to go about doing this?

I'll have to think a little bit about it. The problem is that you need to relate an IP address, to a user, and then to the Community Builder profile. Not too easy I'm guessing.

Probably you'll need to add more fields to the database such that you read and store the username of the current user besides the IP.

Then using that information, you can render a link to the community builder profile from the pin.

Should be doable, problem is time! If you give it a go, please do get in touch so I can upgrade the version with your extension.