Yet another great piece by Stoney G deGeyter, author of The Best Damn Web Marketing Checklist, and CEO of Pole Position Marketing on shady SEO tactics that can kill your site.
http://www.searchenginejournal.com/5-ki ... ay/139546/
The 4th point is a must read. Many marketers out there are still unaware that a no-follow causes loss of link juice from the site just like a do-follow link. It's just that the linked site doesn't receive the link juice.