eboxy is an application for building simple user interfaces. It was originally designed for running a GUI on a set-top box, suitable for use on a TV; however, it can be used for many other purposes. It reads an XML file describing a simple GUI and creates and runs the GUI on the screen.
I wrote this software for my eBox project (a movie/audio playing home entertainment PC), so I could access its various functions from the comfort of the couch using a remote. The eBox project is as much about helping others build similar systems as it is getting a decent entertainment system for myself, so for detailed information on the eBox and how you can set up such a system using Linux, check out the eBox website.