Most major cities have public data portals like this, including San Francisco, Chicago, New York, Boston, Seattle, Austin, Oakland, and so on. Some are more useful than others, I think. (For instance, Oakland is mostly crime-related reports... surprise?)

San Francisco has some great ones that could be used to make new startups... things like street cleaning schedules, maps of every building in the city, the location of every parking space, and so on. You could easily build a niche app to, for example, remind you to move your car when street cleaning is coming by. Or maybe an app to inform you of local graffiti reports so you can be a good Samaritan and clean it up.

It's really great stuff. I love public data sets like this... and I'm actually using Chicago's (and several other cities) in my own work at my day job, so it's nice to see this get some recognition!