tedster - 7:16 pm on Jan 4, 2011 (gmt 0)
My advice to my clients and to myself boils down to one sentence. Make sure Google sees that you are running a true business, not just "a website".
This means that signs of audience engagement are essential in some form - and the more the better.
This is becoming more and more essential, IMO. In specific, it might mean that there is a natural conversation on social sites, or that you have a blog where you respond to comments, or that you have video content that gets comments, shares or embeds. It might mean you have physical world contact information, easily found on your website. It might mean introducing reviews, or enhancing existing features with RDFa - microformats.
But most of all, it means not ignoring any site for extended periods.