"ClickBank is the Internet's largest digital marketplace, where thousands of the web's most popular products are sold every day. Whether you're looking to buy, sell, or promote digital products, ClickBank is for you."

Well finally Clickbank has added a blog to it's site. It started on 3rd April and it says there will be posts twice a week. So far they are keeping to their word. I hope they provide helpful information on affiliate marketing.
http://www.clickbank.com/blog/