http://www.linkbuildingblog.com/2006/11/competitive_web.html
in a nutshell:

-use private registration and since google is a registrar now
-hide your identity behind a network of companys and family members(you could even spread them about different continents, using a delaware inc., a british ltd. a spanish S.L.
-use different registrars
-use different hosts
-avoid design, coding and linking footprints