I had the good luck / misfortune to take a class taught by Jef Raskin (http://humane.sourceforge.net/home/index.html), the inventor of the Mac UI (and other features). One thing that I came to appreciate after reading his book "The Humane Interface" is the sorry state of modern UI, and how we've become accustomed to awkward or difficult to use interfaces because "Hey, that's how it's always been done".

Last night I had a discussion with a chemist friend of mine and I pointed out a simple UI optimization (why Mac's have the menubar at the top of the screen vs on the individual windows a la MS Windows) and she was amazed as realized how the value of such a subtle change impacted her user experience. Yet precisely because we seek "familiarity" in our UI's, we wind up in a vicious cycle whereby established, yet crappy, elements are maintained solely due to age, and novel and useful innovations are avoided in an attempt to be more user friendly. Ironic.

Rather than focus on the warm-fuzzy-look-and-feel elements of UI design, Jef's book discusses lower level, measurement-based heuristics for evaluating interfaces, and I must say that just by understanding his examples, I've become a better critic of design.

My only caveat: I mentioned that I was misfortunate in taking the course. I say this because, though he didn't mean it that way, his theory was much like Swift's "A Modest Proposal": lots of salient points which led to an unacceptable conclusion. If you want to see what I mean, download Jef's "THE" (The Humane Environment) which is his conception of an ideal UI.