Firefox (3.0.3) doesn't allow me to enter only a socks 5 server.
I enter localhost and 1080 and click ok, but when I go back to the proxy settings page the socks settings are gone. Also, if you having anything in the http box you get a blank page when attempting to browse the web.
However it does work in Internet Explorer, just be sure only the socks fields are filled in..

Great Job!
Thanks!!!