Even if my friends wanted to invite me to something, I would rather it come from them saying "hey check out this site" via some IM network, rather then an form

Even if my friends wanted to invite me to something, I would rather it come from them saying "hey check out this site" via some IM network, rather then an form email from the website. I get too much spam as it is, I don't want advertisements to go use your product (which is spam to me) Bottom line: If you site is useful enough, you don't need to spam people via email to get them to join.