Enso is now freeware. If you run Windows (and there have been allegations of a forthcoming Mac version, although Quicksilver is very good), you need to give this a try. You’ll never know how much time and attention you are wasting in your Start menu if you don’t. And don’t worry, you’ll still have access to something Caps Lock-like – it just won’t trip you up if you fat-finger Shift or Tab, ever again.

The theories behind Enso come from the work of the late Jef Raskin, who more or less created the Macintosh interface. After that went the way it went, Jef left Apple and went on to take ideas from the Mac and combine them with ideas from the command-line world, as well as some rather lovely new ideas like quasimodes, into the legendary, commercially failed machine the Canon Cat. (For a taste of why the Cat was loved by its users as well as why it was discontinued, take a look at Raskin’s open-source project Archy. Not very beautiful, indeed forbidding-looking, but run the tutorial video and its power becomes clear.)

The theories are Raskin’s, but the code behind Enso comes from his son Aza and his now-ex-colleagues at Humanized. As you can see from the Humanized website, the mistake of neglecting appearances was not made again in Enso. It is as gorgeous as it is snappy and resourceful. And unlike the first-glance inscrutability of Archy, Enso is simple – it pulls one salient idea, that of “leaping,” from the elder Raskin’s work and snaps it right into Windows as though it’s always been there. (Note that the actual “leaps” from the Cat and Archy are full-text searches, which Enso doesn’t do.)

Aza Raskin and his co-Ensoers are (mostly) now employees of the Mozilla Corporation, specifically of Mozilla Labs. Labs is already getting up to a lot of interesting stuff, and it is about to get a lot more interesting. I hope that Enso development doesn’t completely abate, or that we get something in a similar vein but even more awesome.

(Want more UI thoughts? Here’s a video of Aza Raskin doing a tech talk at Google. If that doesn’t grab you, root around some more in the Humanized weblog. And, I am sorry I was away. To quote Ze Frank, I didn’t forget about you, and I like you.)