Ubiquity is a time-saving Firefox extension that simplifies common web activities by letting you give commands to Firefox. Ubiquity includes about 80 commands for speeding up common web activities (searching, translating, mapping, emailing, etc.), but also provides an API so you can write your own commands using Javascript. You can also share the commands you write, and subscribe to commands shared by other users.

To make it easy for users to run these commands, Ubiquity provides a unique pseudo-natural-language input method: You type what you want to do, and Ubiquity guesses what you mean and suggests the best-matching commands. For instance, you can select some foreign-language text on a web page, hit a hotkey to bring up the Ubiquity interface, and type "translate" (or just type "tr" and let Ubiquity figure out that you mean the translate command); then hit enter to have the selected text replaced, right in the page, with a translation to your language.