One of the things which has annoyed me about Firefox's "View Source" feature for a while is the lack of a back button (and perhaps an addressbar for good measure). This is most noticeable when you've jumped into one of the stylesheets or scripts linked into the page, and you now want to go back and check exactly how that gets used in the main page.
Sometime over the last year or two, I eventually stumbled across a way involving the use of the Backspace key, which apparently does do this. I suppose it's ok in a pinch, but there's got to be a nicer way (or at least some addons which do this!)
After a brief search tonight, I found the answer here. Apparently, if you just append "view-source:" in front of the URL for the page you're trying to check on, this will display the source code for that page within the browser window itself, allowing you to use all the standard controls you're used to. Sweet!