Abstract: In one implementation, a computer-implemented method includes receiving, at a computer system and from a first computing device, a request to access a simulation of an application running a second computing device; identifying, by the computer system, one or more types of input that are available on the second computing device and that are not available on the first computing device; generating one or more controls for each of at least a portion of the identified types of input; instantiating, by the computer system, a virtual machine that simulates the second computing device; and providing information to the first computing device that causes i) an interface for the application as executed by the virtual machine to be presented by the first computing device and ii) the generated controls to be presented by the first computing device in association with the interface.

Abstract: In one implementation, a computer-implemented method includes receiving, at a computing device and from a computer server system, digital content that is for sale and that is received without having yet been purchased by a user of the computing device; storing the digital content locally on the computing device in a manner that prohibits user access to the digital content; after storing the digital content: receiving user input that indicates the user is purchasing at least a portion of the stored digital content; and in response to the received user input, storing information that indicates the user purchased the portion of the digital content and providing the user with access to the purchased portion of the digital content; and in response to detecting that the computing device is communicatively connected to the computer server system over a network, providing the stored information to the computer server system.

Abstract: The functionality of an ereader module that is displaying an electronic book (“ebook”) is extended. A user identifier specifying a user using a client device executing the ereader module and an ebook identifier specifying the ebook displayed by the ereader module are received from the client device. One or more layers associated with the user are determined. One or more layers associated with the ebook are determined. A list of one or more layers is assembled. The layer list is transmitted to the client device. The client device enables the user to select a layer and use the selected layer to interact with content of the ebook.

Abstract: A touch-sensitive display of a mobile device is used to control applications executing on a host computer. A communications link is established between the host computer and the mobile device. A graphical user interface (GUI) from the host computer is delegated to the touch-sensitive display of the mobile device via the communications link. The mobile device is adapted to show the delegated GUI on the touch-sensitive display of the mobile device, wherein a user can interact with the displayed GUI. The host computer receives data describing the user interactions with the delegated GUI shown on the touch-sensitive display of the mobile device via the communications link. The host computer executes an instruction on the host computer based in part on the received data describing the user interaction.