Subdomain websites can be submitted to search engines just like your main site. If your website is doing alright in search engines, then imagine having five more websites out there for spiders to find. Five more listings means that Web surfers have five times as many ways to find your network of websites.

More and more search engine algorithms take into consideration number and ranking of sites that link to you. By linking your sub-domains to your main site and to each other, ranking of all of your sites is improved.

Your subdomains provide a great area for testing banner exchanges and other advertising resource mediums, withotu cluttering up main site. Each sub domain will carry it's own traffic statistics, and campains can be tracked effectiantly by ones self with server stats or other preferred tracking methods. (Another article)

Get creative and branch your services and products out between your subdomains and keeping them all connected via your main site. It will increase your keyword density and rankings per sub domain and most consumers are more confortable working with a specialized area then a one-stop shop.