Also of note: textbroker.com : content creation as a service, with an API. Used them for several hundred pages of content for a client. (If an enterprising HNer wants to do same with better API and more upmarket writers, I would use it.)

The wired article c3o links to below (his post is [dead] for some reason though) is a fascinating look at how Demand Media works.

Spamming the internet with millions of articles of marginally useful content... I have to admit it's an audacious idea.