[tagawa]

Surely the first place to start is Jakob Nielsen's http://www.useit.com

Ignore the ugliness and you'll find practical advice in the reports and Alertbox articles although his opinions are sometimes controversial and shouldn't necessarily be followed to the letter. Nevertheless they'll undoubtedly increase your awareness of the variety of user types out there and encourage you to think from their perspective, which is ultimately what good UI design is all about.

[indspenceable]

Doesn't it seem like a bad sign to say: "Here is where you should learn about UI - just ignore the bad UI." For all I know there is lots of good content there, but I'm immediately turned off of learning about UI from someone who can't even be bothered to make it easy to parse his frontpage.

[isleyaardvark]

But it's not bad UI per se. It's just not particularly attractive.

To put it another way, I've never had a problem finding what I was looking for on his site.

edit: here's another example of what I'm talking about: http://37signals.com/svn/posts/3215-liveauctioneers-an-unlik...

[petervandijck]

Ugliness != bad UI.