I have stumbled accross ChangeThis a while ago and usually find very interesting content there. I like the way they serve the content and their motivation behind it. Here's what they say about themselves:

ChangeThis is creating a new kind of media. A form of media that uses existing tools (like PDFs, blogs and the web) to challenge the way ideas are created and spread.

Here are some of their manifestos that are definitely worth reading:

• The Long Tail: Read his manifesto to find out how unlimited shelf space and personalization can revolutionize your business.
• The Bootstrappers Bible: There's never been a better time to start a business with no money. By our beloved Seth Godin.
• And last but not least: If you want to find out more about ChangeThis, download this manifesto.