@dhouston - Can you give us more insight as to why a) the affiliate program didn't work and b) the referral program worked / what you mean by "2 sided referral program"?

im assuming affiliate is where payment is in the form of $ and to non-users who promoted dropbox and referral is payment of more storage on dropbox (ie- 250 mb per referral more) to actual users. Do you think a mix of the two would have worked well ie- payment of actual $ instead of the 250mb, BUT to actual users.