I would personally much rather hack up a Firefox extension in Python than to try to do it in Firefox's standard plugin architecture thingamajig (Javascript/CSS/

I would personally much rather hack up a Firefox extension in Python than to try to do it in Firefox's standard plugin architecture thingamajig (Javascript/CSS/voodoo/???). You'll still need to do "CSS/voodoo/???" to integrate your extension to the Firefox UI. What you get to do is to use Python instead of JavaScript (a matter of taste), and you get access to Python libraries, which cover desktop-side computing much better than JS.