What's Open is a free service that uses Google Maps to show nearby places that are now open.
The idea is that at 4am, you want to go somewhere to get food, but you don't know what is open at that hour.
What's Open will find all places around you that are currently open, and tell you how long you have until they close.
You are limited to 20 search results at a time (Google Maps limit), so if you find you are only seeing 20 search results at a time,
try zooming in and searching again by hitting the all, food, or pizza buttons.
What's open is also an iOS app, built for both the iPad and iPhone, which you can download on the app store.