Documentation is the design infrastructure of your project.

• It enables good design process
• It benefits all the members of the team
• It provides a shared reality
  

The best way to serve your customer is to design a site that's intuitively obvious, appropriate in its complexity, and easy on the eye. Beyond that, embedded "online help" features are also important, especially since they're so hard to do well.

Nobody ever reads the manual. It's boring. Wordy. Too theoretical.

Nobody wants to learn how something works. We want it to be obvious.

Immediacy rules. Relevance and appropriateness are a big part of that.

Aside from good basic design, there are several simple things we can do to make the "customer experience" better at the level of screen design.

Context-Sensitive Popups	This "just in time" info is the main source of useful help. These are small information boxes that popup when the mouse hovers over something.
On-Screen Directions	Call it an Introduction, a Summary, an Overview, whatever: Well-written (concise and clear) on-screen text tells me Where I am, What I can do, and How I can get there.
Mini-Presentations	Don't just talk about it - "Show Me". Target the 3-to-5 most important tasks and demonstrate them on-screen. The extra effort will be well-rewarded.
FAQ's	Frequently Asked Questions show that you understand the situation ("I anticipate your question. Here's the answer.") If you find you've got a bunch of FAQ's focusing on a particular topic, then you may want to create a mini-presentation.
Site Map	A visual overview of the site representation speeds understanding and can be an excellent shortcut for those who use it. As ever, a picture is worth a thousand words.
Standard Online Help	Includes the usual power tools: Table of Contents, Index and Keyword Search. This stuff is packed with information - The challenge is getting people to use it. Screenshots and graphics help a lot.

Context sensitive info. Available at the moment of need. Lean text. Task-oriented demos. And Pictures.