I really hate how submitting or updating a bug on Bugzilla leaves you at post_bug.cgi or process_bug.cgi, rather than bouncing you back to a URL that actually identifies the bug in question. So, I wrote a Greasemonkey userscript named Termite Misdirection to detect this situation and fix the URL. If your browser supports the HTML5 history API, it should be mostly transparent; if not, then you’ll see the page being reloaded, and you’ll lose the “Changes submitted” etc. message.
I use this Chromium; I’m told it works in Firefox too. (Yes, I know I should submit a patch to Bugzilla itself to make this unnecessary, but that would be more work than 16 lines of Javascript and wouldn’t work with all the existing Bugzilla instances I use every day.)