Use an Old product to sell a new one
At the end of the ebook it has a link to the newer version and something like "If you enjoyed this 2000 edition you'll really enjoy the latest version with 30% new material"
I thought it was a great way to drive traffic, get buzz, and sales. If you have an old product, don't toss it, consider giving it away. You can get it listed in all the Freebie sites and such for good free traffic.
If you want the above mentioned eBook it's called "How to be Invisible" and can be found here:
http://www.canaryislandspress.com/media/HTBI2000.pdf
Success consists of going from failure to failure without loss of enthusiasm. -Winston Churchill