The Poloniex Ruby SDK by Carl Schwope allows API interaction. It includes installation with gem & bundle. It also offers usage that demonstrates GET requests to Public API and POST requests to Trading API. Authentication required to work with Trading API.
Overstock has announced the integration of its online marketplace with ShapeShift to offer customers use of all major cryptocurrencies. Thanks to the integration with ShapeShift, Overstock customers can now pay for purchases with Bitcoin Cash, Dash, Ethereum, Litecoin, Monero, and many other assets.