This audible enforcement is very helpful during development and to "hear" which sites are sneaking in external calls without bringing up firebug, etc.
I have my own firefox extension which I hacked up from an abandoned old firefox extension (called "soundextension" by Torisugari) not suitable for release, but there is a more modern extension here which does most of the same:
https://addons.mozilla.org/en-US/firefox/addon/noise/
The click sounds I use are from old Windows 2000, I doubt XP/7/8 has them, NIMclick.wav and NIMover.wav
https://www.google.com/search?q=nimclick.wav+nimover.wav
I vaguely remember I also had to edit the sound files to cut the volume way down, so my PC sound could be at normal levels while the clicks were much more subtle in the background.
Once your brain is trained as to which click means what, you get a good sense of what a page is doing, sneakily or otherwise. Won't work with websockets though.
Granted, I'm running Chromium (presumably you're talking about Firefox), but the plugin does exist for both browsers.
I don't have the gumption to splunk the code.
I kinda wish either they'd declare each other competitors or embrace each other as compliments.
I used Ghostery for a while but found it redundant and onerous since I also run NoScript. I agree with the parent that said Ghostery was a poor man's NoScript, though Ghostery only blocks known trackers (analytics tools) and will let random evil scripts through. NoScript allows you to whitelist script sources by domain, so you usually see "Enable example.com; Enable analytics.google.com; Enable quantcast.com;", etc., and you can just enable example.com if you don't like the trackers.
NoScript is really important and useful I think. Less convinced on Ghostery. AdBlock is useful but I don't know if I'd call it "important" really; it provides a great visual convenience to be able to read sites without being bombarded by ads, but one can live safely without it if necessary.
However, NoScript is still very useful for (imho) two things: disabling extra functionality that you don't use in exchange for faster loading time, and for browsing on potentially dangerous websites.