This is a very basic Heroku app that serves websockets.

The HTML and JavaScript parts are adapted from
http://www.websocket.org/echo.html

To run locally:

    $ go get github.com/kr/wsdemo
    $ foreman start -d $GOPATH/src/github.com/kr/wsdemo

To run on Heroku, you need a router that provides
websocket support, such as https://github.com/kr/webx