Pidgin Facebook plugin (pidgin-facebookchat)
I’ve just discovered the Pidgin plugin that allows you to chat with friends on Facebook without needing to be signed in to the site (and means you don’t have to use their little chat windows in your browser).
On Ubuntu it’s a matter of apt-get install pidgin-facebookchat. Other platforms available from the project site.
So far it seems to work pretty well, albeit with some disconnection problems when you’re using the plugin and signed into the Facebook site simultaneously. Still, it’s a nifty little tool.
Update 29/11: In the last couple of weeks I’ve found the plugin has stopped working, for me at least. Facebook shenanigans? Anyway, your mileage may vary.