Tom Hunter just requested a new feature which was easy enough to implement.
Invite a Friend
This allows you to send a quick note to someone and invite them to join the forum. If you'd like to give it a try go to your user profile page (click on your username at the top of the page). Once you are on your profile page you should see a "Invite a Friend" link in the upper right corner, click on that and enjoy.
Here's an example of what will be sent to the recipient ...
Hello! I'd like to invite you to join the ThorpForum! The central location for all Thorp T-18/S-18 enthusiasts! Please go to http://t18.net/forum/register.asp and follow the instructions to become a member!