It would be useful to identify when a contribution or event registration occurs as a result of a "tell a friend" message - and link it to the referring friend.
1. Add solicitor_id column to civicrm_participant (we already have this field in civicrm_contribution)
2. Include the referring friend's contact id in the URL's which are emailed to the "friends" (referrer ID):
3. Write the rid (referrerID) to the resulting contribution or participant record in the solicitor_id column
4. On the Contact "Contributions" tab - add a new section to list "Referred Contributions" - and list contributions where solicitor_id = contact_id of contact being viewed.
5. On the Contact "Events" tab - add a new section to list "Referred Participants" - and list participant records where solicitor_id = contact_id of contact being viewed.