Things to do - I find it really hard to find things to go out and do in my spare time, events listings never seem to have something that interests me, same with tourist guides although they can be better. Asking friends is always an order of magnitude better.
I've long thought there is a serious opportunity in connecting organizations who provide fun things to do with people looking for fun things to do. I had an (unpursued) idea a while back to create a single-serving site called, "What should I do this weekend?" Another idea was a subscription-based service that organizes adult "field trips" every weekend.
I've had a lot of success with the CouchSurfers community. It's a travel oriented site, but they also promote meetups for the people living in a city so as to form a tighter, most trusting community. When you throw travel-wise tourists, friendly city ambassadors, and generally open-minded go-out-and-tackle-the-world style people together in a room and have them share stories or plan events it gets crazy and amazing really, really quickly.
I wonder if you could make a list of public events on Facebook, searchable by town. There's a lot of stuff that happens; I just usually don't know about it until too late.
