Idea #1: Craiglist based on location
Real world problem: I want to find somebody who is selling a bicycle -> I go on craiglist and try to find it but most of the ads I see are on the other end of the city. I don’t want to drive to another end of the city…. what if you can have people enter their address on the ad page before they post something. Layout all these ads the way google lays out their “local search” results.
Final product: you search for any item on Craiglist, instead of a list of results based on timeline, you get a map with dots on it. These dots represent seller of an item you’re looking for.
Simple. Very useful.