Mod like this? Tell a friend via IM?
 

Is there some sort of modification where you can input an IM screename and it will ask all your buddies to join your forum? Just like facebook?

I'm sure there isn't but that's a pretty good idea.

The closest thing aside from emailing to people from your own email accounts of your new site, is the Thread Tools Email This button, but there's no list of your contacts there which would be incredibly helpful as a new member to email to people on your list who might like the site they are viewing.

Importing contact lists into each person's profile or into that form page would be awesome and might work.