While Amazon Appstore may not exactly qualify as an "app," it is nonetheless, a valuable download. It's an altogether different marketplace from the official Android Market, so it offers different picks, recommendations, and reviews. The home page opens up to Top Paid apps and Top Free apps, so it's easy to see what's hot. Otherwise, you can search by keyword or browse through categories with ease.
What's more, Amazon Appstore gives users one paid app every day, free of charge. So, if you have an Amazon.com account and an Android-powered device, this one is absolutely worthwhile.