Social software + Web 2.0 + command-line action: YubNub.
YubNub lets you create link shortcuts, like in Mozilla Firefox, after some configuration you could type this into your address bar: imdb life of brian, and have those strings glued to the search URL of the Internet’s biggest movie database. Very handy. Especially for extra-special, custom searching that you only you might be interested in.
YubNub’s superness is that all these shortcuts and fixes are saved in one place. You can reuse others’ commands.
This is a project I think will live to tell its stories.
A product of RailsDay, a 24hr programming contest which spawned quite a few nice usable projects. Winners to be announced.
Update: This summary article on the Web 2.0 conference has enough sound-bites to clue you in on the subject, if you haven’t got the time to read the full wikipedia entry.