I found some funky URI's for access the internals of Firefox. Most of them well documented at MozillaZine.

The most interesting ones are related to the about:cache URI. If you type this into a Firefox or Mozilla based browser you will get links to cached objects in memory, either in RAM or on disk.

What's interesting about this is thats its a great and simple way of snarfing resources because it gives you a list of URL's recently visited that you can just right click and "Save Link As".

Also check out the unnerving about:mozilla page.