Don't forget your robots.txt!
Today I received an email out of the blue from Google, warning me that this site was not being indexed because I had forbidden them from doing so!
My robots.txt file was:
Which in English means "whoever you are, please do not index anything".
Of course this wasn't intentional. Way back, even before I started blogging here, there was a teaser screen shown that counted down the days to the launch of the Dozing Dogs ASP.NET CMS. And since it was pointless for the search engines to index this I set up the robots.txt above.
Of course that's all very clever, but I wish I had remembered to change it after the launch. That's three months of lost Google Juice.