This thread is a fascinating read ... I'm experimenting with many of these things myself at the moment.

One idea to add to the discussion ... surveying your list.

I sent out a survey recently which brought in some excellent information about preferred price points for products, what they most wanted to know, what their aspirations were.

I know many people use the free version of Survey Monkey for this http://www.surveymonkey.com/ but I used Google Forms because a) it's free b) it stores the info in a Google Doc Excel spreadsheet, meaning that you can extract and manipulate the data easily afterwards.

Here's the form I sent to my list: http://bit.ly/9VUDrl

You can even add a custom message after submitting, so I added a thank you gift after the person clicks on 'submit'.

I got some great replies and it will inform what I send to my list in future.