Google does a "C" shape sweep of a page, paying particular attention to content on the nav bar, side links and footer links, see diagram above.
Layouts vary. Positions of your sidebar or navigation vary too.
But with respect to the core markup itself, it’s best to put your main content as close to the body tag as possible.
Google’s c shaped sweep.
If your other elements have to be placed before the content, use CSS to position it before the content instead of moving the markup itself before the content.
Footers are wonderful places to link to other content on your site.
Don’t just ignore your footer.
Place links to recent posts or popular posts in the footer.
Having said that, try to not make it look like a link farm.(nettuts)
Net tuts Search Optimization 101
dated: September 2009
By Siddarth
Links
WebpageSEO 101
Page 104 SEO Book
by Aaron Wall
Links
Aaron Walls SEO website
seo book.com
View the PDF of the SEO book.