Hi Ricky,
One thing that Jimmy D. Brown suggests in the first of his List and Traffic videos is to think of your list members as more than "subscribers," more than "potential customers" -- think of them as "marketing partners." It's a concept most list owners don't consider.
This concept can work whether it's a "make money" niche where you convert subscribers to affiliates, or any other kind of niche... even one where your subscribers are only interested in... say.... braiding hair!
For example, you could send an email like this to your list: "Several people have asked if it's okay to share my ebook on hair-braiding tips with their friends. That wouldn't be fair (to me or the people who've paid money for that ebook). So please keep the ebook to yourself. However, I've written a short report that you MAY give to your friends. It doesn't include all the tips in my ebook, but I've shared a few tips that your friends may find useful. You can send them to.... (URL of your website/free download page) where they can download the report for free...."
Of course the free report would promote your product.
I highly recommend Jimmy's List and Traffic video newsletter. He provides amazingly detailed, step-by-step (with examples) content... in video, MP3 and PDF format. It's only $10 a month, but is easily worth 10 times that.
Find out more here:
http://listandtraffic2.com/go.php?1711
Disclosure: that's an affiliate link.