jumpstart.com ?

it sounds completely illegal to me... taking money for renting an apartment without being a real estate agent?

i think you also mean jumppost.com

sure, jumppost.com. My bad. Anybody used it?

This site is a bit of nonsense. Contacting the current tenant to get a lead on an apt? Knowing the apt is going to be available is a distinct advantage. But securing the apt is up to the LL not the current tenant.

But if the website does all the work of getting a prospective tenant lined up (i.e. does the work of a broker), why not get a kickback from the website to give them the first heads up?

Does this work?
Somehow I doubt it though I applaud the effort since I guess they are only getting paid for performance, not taking an upfront fee. Personally I'm not sure why a tenant wants to waste time just to potentially make $500 with all of the flakiness of the rental market.