I'm about to start creating one. I think FS needs a UI comparable to FreePBX or similar. It's the next project on my list. It would certainly be a boost to the FS project and user acceptance.
Be sure to check with Bougyman on IRC. He is planning on releasing an open-source, MIT-licensed FS-GUI w/ underlying framework. Last I heard he said week of June 15. Note: he said that it will require Ruby plus Rack and PostgreSQL.