A quick Google Maps mashup of two open datasets from San Francisco:
Shady Eats allows you to look for food trucks near your current location that have street trees nearby to hide from the sun. Because you're a developer, and giant balls of hot fusion scare you. :)
Live example at http://chrismetcalf.github.io/shady-eats/!
I've also written this up in a blog post and demonstrated it in a YouTube video.