Amazon has launched their new [Kindle Matchbook](http://www.amazon.com/gp/feature.html?ie=UTF8&docId=1001373341) service, which reviews your previous book purchases to determine if you’re eligible for discounted Kindle versions. As you would expect, only a few publishers are signed up at the moment, but hopefully this program will go as time goes on.[^fn1]
[^fn1]: Currently, I have about 20 books that I could get eBook versions for, ranging in prices of $1.99 to $2.99.