Mozilla just released the list of official winners of its Firefox plugin contest.
Personally speaking, I use the Web Developer Plugin by Chris Pederick (though others prefer Firebug), Better You Tube by Lifehacker and Colorful Tabs, I’ve messed around with the life streaming app Snowl, but IMHO it needs more work.
Of the new Mozilla list the one that catches my eye is Pencil.
Plugins are still a fairly geeky kind of thing, however, I think they’ll become more mainstream as the distinctions between the browser and the desktop breakdown. They also offer opportunities for organisations to manage their communications with customers and clients more efficiently, e.g. the e-bay Firefox extension released last year.