Jakob Neilson's site is a treasure trove of usability information.
http://www.useit.com/
37 Signals will often write blog posts outlining particular design decisions in their products.
http://www.37signals.com/svn/
For a more specific topic, I have been researching typography. Something really simple to do (for which I am in the process of doing); get your text baselines to line up ("baseline rhythm"). It will make your site easier to read. Here's some great writeups on the subject.
I constantly check http://www.styleboost.com
It's not really about usability but more like a barometer of what's considered good design these days. If I ever need design inspiration this is where I trek to first.
I'll toss another hat in Tufte's ring. His stuff can be pretty meta, but once the concepts are in your head, you start looking at design much differently.
If I hadn't read 'The Quantitative Display of Visual Information' I think that my design work would be much more cluttered and confusing. Reading the book actually made me want to be a better designer -- I knew, instinctively and through his demonstrations, that my work was definitely not up to par. Any book that can cut through the dense pretenses of a cocky young designer deserves some respect ;D
Sometimes it's also helpful to experiencing good usability. So I suggest using OS X, after awhile I found myself looking at software in a different way.
We're looking for good examples of sticky signup processes. Asking users for the 'fun' info and sneaking in the necessary nuts, blots, and email confirmation later seems like a good way to go. Thoughts? Examples?
How to use contrast to your advantage- http://www.gomediazine.com/design-tip/rule-three-contrast-co...
Use colors that have varying intensities, not just differnet colors. Focus on how it looks in greyscale http://www.gomediazine.com/design-tip/becoming-a-master-desi...
Visualizing Fitt's Law http://particletree.com/features/visualizing-fittss-law/
Software Has personality. http://blogs.adobe.com/lightroomjournal/2007/09/lightrooms_g...
Copy sites you like, such as: http://orderedlist.com/articles/single-line-css#comments or http://www.joyent.com/
How to make your designs suck less: http://jimwhimpey.com/blog/2007/simple-ways-to-help-your-des...
Load faster, by doing a low-res version first. http://www.wait-till-i.com/index.php?p=464
How to do sound design http://www.boxesandarrows.com/view/why_is_that_thing_beeping...
More on Sound Design http://digitalmedia.oreilly.com/2007/03/22/how-to-make-user-...
Use smart color pickers http://news.ycombinator.com/comments?id=6434
Whitespace Matters! http://alistapart.com/articles/whitespace
You can make a UI feel responsive, by minimizing the number of clicks http://tantek.com/log/2007/02.html#d19t1813
Write Production UIs, never use placeholders http://a-simian-mind.blogspot.com/2007/03/user-interface-is-...
A gradient Tutorial http://9rules.com/blog/2006/08/a-gradient-tutorial/
Aza's tips http://ajaxian.com/archives/death-of-the-desktop-by-aza-rask...