I was in my Mobile Development class one day, and our assignment was to test out an HTTP POST request on iOS. I just wanted a simple test server, but I couldn't really find any that suited my needs. That turned into Browsver.
Browsver uses a main server and a "browser server", communicating between them using a Websocket. When the main server gets a request from a user, it forwards the GET and POST parameters as well as the URL to the browser. The browser handles this data, and sends back a response through the Websocket.