Rajesh has this fine link to Patrick Spain's opinion about valuable content services:

"As I look across the landscape of online content, I have observed some things that clearly work:

1. Users don't care where the information comes from. They just want to know what is out there. So failing to include the free Web with your paid service is a big mistake.

2. Failing to provide premium for pay information on your free search is just as big a mistake. If the answer to a question relates to health or wealth, people will pay.

3. You have to be very clear and honest with users about what is free and what is paid. Don't try to charge for content that is free elsewhere.

4. Users want a fast, intuitive interface to do their searches. Our typical users decide in a couple of seconds whether we are a useful service. When they first come, they will not take the time to tell us that they want results only in English and Turkish, as I had to do with Factiva.

5. Advertising on a for-pay site that does not interfere with the use of the site (as much of the advertising on free sites does) has no deleterious effects on sign up rates or retention. Done right, advertising enhances the attractiveness of a publication. Just ask The Wall Street Journal.

6. Free search and free trials are essential to demonstrate to users that you can be useful to them.

7. Enable the ability to save and repeat searches, store knowledge and convert that knowledgeable to usable form as a report, a contact, a spreadsheet or a presentation.

8. You can't charge just for content. Charge for the convenience and delight of using your service. Why does Starbucks get 2-3 times what McDonald's does for a cup of coffee?

My feel (being biased extensively) is that this site and most Creative Weblogging sites follow these IMHO very helpful rules. What do you think? What would you like to see in the next release of CW sites?