For some people a web site only needs to be a 'business card on the web'; a place to send people to see information about your business or organization, but for most of us, we want the site to be found all on it's own.  For a web site to be an effective marketing tool, it should first be easy to be found, then when people go there the site should be impressive enough to draw visitors within to see the content, and the content should convert the visitor into a customer.