Carsten Cumbrowski posted a article, "50 Questions to Evaluate the Quality of Your Website" that is useful for website owners, designers, bloggers and search engine marketers to consider.
Here is a long and pretty detailed list of questions that a website owner should asked himself about his own website. If the answer to every question that follows below was answered with yes, you can be very pleased with yourself and consider yourself the top of the crop, because most websites have flaws for a number of different reasons, mostly related to the limitation of resources and sacrifices that must be made as a direct result of the shortage.
Consider Carsten's questions in the various categories:
Accessibility
Is content structurally separate from navigational elements?
Navigation
Are links labeled with anchor text that provides a clear indication of where they lead.
Design
Are the color choices visually accessible? (For example high enough in contrast to assist the colorblind and visually impaired in reading the site appropriately)
Content
Do you update the content regularly and don’t live by the phrase “set it and forget it”?
Security
Is customer data stored online? If so, is this database appropriately safeguarded against external access?
Other Technical Considerations
Does the site load quickly - even for dialup users?
Other Marketing Considerations
Is the website properly optimized for search engines (essential text emphasized, title tags relevant, title text presented in H1, outbound links reliable and contextually related, etc)
Legal Stuff/Re-Assurance/Legitimization
Privacy Policy up (especially if you collect data, email, names, and web analytics tracking cookies)?
Review the reset of Carsten Cumbrowski's article, "50 Questions to Evaluate the Quality of Your Website". It's worth a bookmark.