http://www.yougetsignal.com/tools/web-sites-on-web-server/
A reverse IP domain check takes a domain name or IP address pointing to a web server and searches for other sites known to be hosted on that same web server. Data is gathered from search engine results, which are not guaranteed to be complete. Knowing the other web sites hosted on a web server is important from both an SEO and web filtering perspective, particularly for those on shared web hosting plans.
