I am embarking on a project to create a "refer-a-friend" module and it's associated registration page.  We are going to allow a registered user to add the email address of a friend, and a comment, that will be stored in the database FriendReferals table, the GUID returned, added as a Querystring to a hyperlink and emailed as a link to our registration page, along with the referrer's comments.

I'm planning to use the "friends" email address as an identifier in this FriendReferals table, and disallow future "friending" emails should they register.

Using the User Profile, I plan on adding the "refer-a-friend" GUID as a hidden field, and adding a custom event handler to update the FriendReferal table upon completion of the sucessful registration.  My current plan is to use the UserGUID (if possible), to associate the 2 accounts.

The purpose is to refer ones' friends to the site, and be able to track who refered whom. 

First, does anyone have any comments on the plan, or any been there done that advice?

Second, would this be something of interest for adding to the project eventually?

Thanks!