That's really nice and a clever idea. That said I think it will fail because the users will not be able to answer the 'what's in it for me' question in a positive way.<p>Pay-it-forward schemes tend to die after only a very few cycles (1 or less). Still, some people will do it so it would work as an extra revenue stream.<p>If you want to improve on the scheme you might add a 'pledge' component where you ask the users on the day they sign up that they pledge to pay it forward if the site successfully finds them a long term relationship (assuming that is what they are looking for). Then when they sign out you could remind them off their pledge. This should likely be tied to a one-time payment rather than something recurring.