Need to download the image that is on the webpage? Try about:cache.

Here are some more about commands.

about:

Just typing “about:” will show general and version information. It’s kind of short for about firefox 🙂

about:mozilla

It’s a firefox easter egg. Try it.

about:blank

Shows a blank page.

about:config

Shows Firefox configuration.

about:cache

Shows information about Firefox cache. You can even browse the files in the cache

From here.