I've always wanted that feature. Very helpful when doing javascript development... So I was delighted when I saw View Post-rendered Source, that there's a plugin to do it! That's helpful!

Then I read the first comment from bubu,

hmm, if you select some text in Firefox, and press right button of mouse and choose there View Selection Source, then it will to show generated html source (e.g. modified with javascript), not that wich is downloaded from server.

I guess I just assumed nobody did such thing to bother searching *sigh* Great work Firefox!

PS: Talking about Javascript.. I'd talked about recording web apps before whilst experiencing testing pains rushing for my earlier projects. Now it looks like somebody did a javascript-based record-what-you-did framework for functional testing. Good potential, as long as it works even on relatively javascript-twisted apps! But I must say.. it needs to couple with http conversation recording to truely kickass...