
The Office Live Website has a good series of articles for website owners and business owners [similar to Microsoft Office Online].
An interesting article by Jeff Wuorio talks of item that one must avoid putting on your website or even blog.
Your photo on the home page.
Your Web site should be all about the viewer, not about you. You need to first get them interested.
Undue jargon and techno-speak
Keep your copy and content straightforward - if need be, have a non-expert review it for clarity.
Bad links and outdated material
Nothing can mislead or alienate your visitors more than basic business information and other content that's obviously outdated or long since irrelevant. Same with links that send users to error pages.
Visual (and audio) overkill.
Overly flashy intros with loud, pulsating music can take forever to load and cause users to flee. The technology needs to be there for a reason, not just to impress people.