We have noticed that MailChimp emails allow for a 'Forward' button to be added to them, which when clicked allows users to enter a friend's name, email address, and note and have the email they just read be forwarded to another contact. We feel this would be extremely useful for our (and other schools') word-of-mouth marketing efforts, especially when it comes to recruitment and increasing event attendance.

Link to MailChimp email sample (Navigation bar near the bottom labeled with "Thanks for reading!..." text includes 'Forward' button on the far right.)