Browsing the www.searchengines.com I came across an article strongly discourageing using multiple doorway pages (pages with no content connected directly to your site, serving as gateways to the site scoring high in SE rankings). It says multiple doorway pages will be tracked by spiders and penalized in SE rankings. On the other hand, this is exactly what many SEO companies do. Actually, how can a spider know a page is just a doorway page and not a true homepage of a particular section of your site? After all, it has the required keyword density (that's the major assumption creating a doorway, right?), and meets most of the criteria set by, e.g. Google (it's not too big, plain text to the most part)