I would really like people to be able to use my locked computer to surf, so I would like some way to run a browser on login screen. So can I make GDM run Firefox in some way? It would be cooler if I could have a browser as a screensaver, but that seems a bit harder.
Please ignore all the security problems with this, if you let someone use your computer you have lost that race anyways. Though of course it would be nice to have a browser running as another user.