Some definitions

"Think aloud" is an element of usability testing in which the test users describe their reactions to the design being reviewed.
Two types of think aloud are:
CTA: Current Think Aloud, in which the users give the usability engineer a description of their reactions as the test progresses,
and
RTA: Retrospective Think Aloud, in which the user describes those reactions after the test is over.

Nielsen Usability Best Practices Video

From eWeek via Microsoft's DevSource:
Designing Your Applications for Usability

Usability is a collaborative effort, often done by committee. How can developers maximize the effort to make their applications lovable-or at least easy to use? Guru Jakob Nielsen gives his advice on best practices for programmers.

WebReference: How to Create User Friendly Web Sites

WebReference:
How to Create User Friendly Web Sites

Vitaly Friedman: Usability & Accessibility Links

Vitaly Friedman's Web Developer's Handbook

Find the usability/accessibility section -- lots of great links.

Articles on Colour

UK Builder
Colourful Language: Guidelines on using colours in user interfaces
Make the Right Colour Choices

Giacomo Mazzocato's The Accessibility Color Wheel
Neat code that lets you instantly view samples, and also checks for deuteranopia (insensitivity to green), protanopia (insensitivity to red), and tritanopia (insensitivity to blue).
[Contributed by Eric Novins]

UK Builder on Usability

13 Design rules that every Web site designer should know about

Back to the Drawing Board for Usability

Writing for the Web: It's a Usability Issue

Reduce Visual Clutter to Improve Usability

"How did it make you feel?": The importance of Interviewing Users

... and much more. UK Builder has a solid content base about usability.