There was lots of debate on paid content at the AOP summit this week.  I've distilled down the examples and insights into five key steps:
1. Focus on a core audience
2. Have a free tier to drive traffic
3. Develop intelligent content
4. Work out your pricing structure
5. Be prepared for the operational and technical challenge
See the full version of the article at :http://www.penmaen-media.co.uk/index.php/2009/10/how-to-build-an-online-paid-content-strategy/

I'd be interested in the experiences of other publishers in this field. 

Carolyn