We present a system, called Cygnet, makes it easy both to use and to implement media-rich interactive cloud services. Usage simplicity is achieved by providing a simple but powerful mechanism that makes an I/O device a first-class network-accessible resource that any user can dynamically "bind" to any service at any time. Implementation simplicity is achieved by providing a development and runtime environment that is identical to that of a typical Linux distribution running on a local machine. In Cygnet the cloud is thus transparent to both developers and users, the latter of whom concern themselves simply with choosing the I/O devices via which they wish to interact with their services. The system supports all classes of services and is optimized for the difficult class that requires a GPU to render content in real time. Designing and implementing a cloud-transparent system for that class presents a number of significant technical challenges. We describe how we overcame those challenges and then evaluate the performance of the system's cloud-based GPU rendering.