Important facts to know about Google SEO:

• It is better to have a barebones site live earlier than to wait till you have a perfect site ready.  Google gives more importance to sites that are older and have been live longer.
• Incoming links to your site are very important to getting a good ranking.
• Web pages should contain at least 200 words of relevant text.
• Your site should be updated at least monthly.
• You should design each page around one or (at most) two key phrases.  Ideally every topic should have its own page.
• All else equal, websites with more pages rank better than sites with fewer pages.
• Files closer to the site's root are given greater importance.
• Google ignores pages and links with session IDs embedded.  Specifically, pages with "&id=" in the URL are not indexed.
• Generally it is better to use plural forms of keywords, and to use absolute URLs over relative URLs.
• The "Keywords" META tag is ignored by Google.
• Text links are better for SEO than graphic links.
• A hierarchical link structure is better than a mesh link structure, because the latter distributes PageRank amongst all pages whereas the former assigns higher PageRank to more important pages.

And finally, Google ignores Flash and JavaScript.

Kuler is a pretty cool application, although I'm not clear on why they decided on 5 colors per theme.  I decided to break my websites down into 5-color themes, and here's how they look.