Amazon wants to make sure you’ll buy as much as possible within their own ecosystem. You’ll be able to add Android apps, but those app will come from Amazon’s own Android AppStore.
There are over 17,000 apps in Amazon’s store with applications. It’s a tiny percent of a total number of apps available for Android devices. In mid-October there was more than 500,000 apps in Android Market!
However, before getting down to hacking Kindle Fire’s system, it’s good to check what’s available at Amazon.
How to browse Amazon AppStore
1. Go to Amazon’s AppStore homepage.
2. You can browse by using a search box. A list of results will display only items from the AppStore, not from all Amazon departments.
3. You can also use a left sidebar and select a category you’re interested in. There are 2,700 apps in Books & Comics section. Not that bad!
Actually I was surprised to find Kobo, Aldiko and Bluefire Reader. Get those apps for your Kindle Fire and you’ll be able to read books in epub format from many sources!