There's a little bit of buzz going on about Ubiquity, a UI enhancement for Firefox. Firefox already has hundreds of UI enhancements, but this one is a little different. If you've used Quicksilver on Mac OS X, you may notice Ubiquity feels somewhat similar to it. Basically, you can take something (a piece of a web page) and quickly perform an command with/on it.
The commands are nothing more than javascript snippets. But, because usable web APIs are growing in number and usefulness, Ubiquity has the opportunity to create and fill a need we never knew we had. There are already Firefox extensions that do a lot of what Ubiquity can do now, but Ubiquity is a framework, like greasemonkey, that allows developers to quickly build usability tools for users.
For a 0.1 release, Ubiquity comes with lots of commands. Working with search engines, social web sites, page modification, and browser manipulation are all possible. For example, you can highlight a paragraph of a German website, press alt+Space to pull up Ubiquity, and type "translate this to english". A preview shows what the text will look like after the translation, and pressing enter actually modifies the page source.
There are still some major issues that need to be addressed. For one, the distribution model for commands uses subscriptions. That is, you subscribe to a command, and any changes the developer makes to that command are automatically reflected in your copy. A "trust network" is in the works, but until they have something acceptable, I would avoid subscribing and instead just copy the command source. It's a simple cut and paste to add commands. The commands I've seen so far are short enough that you can quickly scan through the code and see what's being done.
Another issue is bandwidth usage. Most commands have previews that are updated as-you-type, so typing "google elephant" actually does Google searches for "e", "el", "ele", "elep", "eleph", etc. Using tcpdump in the background shows a lot of activity when using Ubiquity. A brief delay would be enough to cut out most of it.
Anyway, I'll keep using Ubiquity and see if it really does make life better. Between this and surfkeys, I expect my mouse usage in Firefox to drop substantially. That's one step closer to the perfect UI. :)