I have some smaller sites that I have considered consolidating under one domain to save some hosting fees. What are your thoughts on the SEO effects of moving from abc.com to abc.mydomain.com and masking the redirect. Would the search engines still see this as a uniquie website or only see abc.mydomain.com and xyz.mydomain.com have the same IP address. With the masking, if you typed abc.com you would be directed to abc.mydomain.com; however will still see abc.com on each page you surf.