GUI design techniques to enhance user experience

What techniques do you know\use to create user-friendly GUI ?

I can name following techniques that I find especially useful:

• Non-blocking notifications (floating dialogs like in Firefox3 or Vista's pop-up messages in tray area)
• Absence of "Save" button
  MS OneNote as an example.
  IM clients can save conversation history automatically
• Integrated search
  Search not only through help files but rather make UI elements searchable.
  Vista made a good step toward such GUI.
  Scout addin Microsoft Office was a really great idea.
• Context oriented UI (Ribbon bar in MS Office 2007)

Do you implement something like listed techniques in your software?

Edit:
As Ryan P mentioned, one of the best way to create usable app is to put yourself in user's place. I totally agree with it, but what I want to see in this topic is specific techniques (like those I mentioned above) rather than general recommendations.

If you do give the user a question, don't make it a yes/no question. Take the time to make a new form and put the verbs as choices like in mac.

For example:

 Would you like to save?    
     Yes        No

Should Be:

  Would you like to save?
    Save        Don't Save 

There is a more detailed explanation here.

Check out the great book Don't make me think by Steve Krug.
It's web focused but many of the conepts can apply to anything from blenders to car dashboards.
Topics covered:

• User patterns
• Designing for scanning
• Wise use of copy
• Navigation design
• Home page layout
• Usability testing

He also has a blog called Advanced Common Sense

And some random UI related links:
- User Interface Design for Programmers by Joel Spolsky
- 10 Usability Nightmares You Should Be Aware Of