The 21 Bitcoin Computer is the fastest way for developers to learn Bitcoin. It has everything you need to build your first app in a weekend: a micropayments server, a full copy of the Blockchain, and a command line interface for programmatically mining, buying, and selling digital goods for bitcoin.
If you can code it, you can sell it. The 21 Bitcoin Computer allows you to monetize the previously unmonetizable. With it you can lease out access to WiFi, sell digital goods to anyone on the internet, or even code a discount-hunting intelligent agent.