Problem: It's Sunday afternoon, or Friday night, or similar. I'm with a few friends, and we'd like to go and "do something". We don't do much research in this mode (we just want to do something right now), so we are pretty constrained to places we have been before. This generally leads to: cinemas.
Potential solution: Spotify/8tracks/Yelp for activities. I should see things like "go hiking in the Pearson-Arastradero Preserve, 10 minutes drive from here", as well as things like "hookah bar in Palo Alto" or "Dave and Busters, 30 minutes drive".
Chances are, I'll also enjoy things that people my age like. Also, the filtering doesn't need to be great - I'm more than happy to look at a list of 20 choices. Currently the problem isn't finding the perfect activities, it's finding activities at all! (It's very easy to be in a lazy mood and believe that there is nothing to do - the solution should show that that isn't the case).
Cool twist: A friend of mine, Jesse, suggested that this could be a great feature of Zipcar. He first noted that Zipcar should have a guestbook, which was quickly combined with this problem, leading to Zipcar users reviewing/noting the places that they used the Zipcar to visit. Result == hyper localized Yelp, with broader reviewer base (remember, the vast majority of Yelp users do not write reviews, they purely consume), and a perfect unoccupied time for the reviews to be written (by passengers, while driver is taking the car back). Of course, the chance of Zipcar doing this is close to 0.