How do you guys host your sites? If you've got 10 AdSense/Amazon/whatever sites, do you host them all with the same hosting company and on the same IP? Or do you separate them? I don't really see the point in separating them since they will all be linked together anyway. It's just that in Google's eyes, won't the Web 2.0 properties, article directories, and in general all the SEO work you do be obvious? After all diversity or not you can only make as much unique links as there are web properties out there. Links other than those of common web properties won't be easy to get.