Real Kiosk is a Firefox 2.0 - 3.0 extension that defaults to full screen, disables all menus, toolbars, key commands and right button menus. Alt+Home still takes you home.
You can enable Navigation toolbar by adding the following to user.js:
You might want to remove the print dialog by adding following lines to your user.js:
Notice that the user can still close Firefox with for example Alt-F4 and get access to your computer. You might want to prevent this with a suitable utility program for your operating system.
Caution! R-kiosk extension can be removed only in Firefox Safe Mode. Howto: http://kb.mozillazine.org/Safe_Mode_