This is great.. why dont you pursue further? Looks like some of it is coming from 4sq api, I can help you there if you are stuck.

Kudos on working on it, and hope you find time to continue building on it. One specific feature that will make it so much easier is if there was a way to bootstrap your list. May be display top tourist locations to start with.. you can also search for tiplists on foursquare to give user starting point. Not sure if you already do that, and I just couldnt figure out..