The way Opera deals with this is to have opera:config be a searchable webpage with hundreds of options that can be changed, nearly none of which can be changed

The way Opera deals with this is to have opera:config be a searchable webpage with hundreds of options that can be changed, nearly none of which can be changed from within the main Preferences UI. Firefox could have an about:config page that's a webpage with a list of every crazy little option that could be changed and the remove all the little used options from the Preferences UI. I don't see a need to completely eliminate the option but put it somewhere only advanced users will go. (P.S. I find the web interface with a search box significantly more friendly to use than a native listbox control as is currently used for the advanced options).