[frikkinpornster]

That would only work if each new site had enough content on it to stand alone, and to get the SEO advantage each would need to be on a separate IP address so you would be cannibalising a single good site to create a bunch of smaller sites that would need to be promoted separately. Sure they could operate as a network passing link juice between each other but its going to take time to get each one up in page rank/traffic etc. Seems like a bad move unless you plan to go this way from the very beginning and you're prepared to put in the effort straight away