I was recently discussing Fwd:Vault with a typical end user, specifically how our service is completely oriented towards people who simply cannot or will not bother with anything technical. She whole-heartedly agreed, and expressed her mindset as follows:

• Just make it work.
• Don’t frustrate me.
• Don’t break on me.

I think those three sentences are the best litmus test for usability and user interface design that I’ve ever seen. They apply to software in any state, planning to released, and always provide an honest assessment (as long as you’re honest with yourself). Eye tracking and usability testing are great when you have the time and resources, but any developer can run this test by himself from his desk in about 5 minutes. Try it yourself on your current project, and see if you don’t uncover an improvement of some kind.