1. A computing device comprising: a processor; and one or more computer-readable storage media having computer-executable instructions stored thereon that, when executed, provide a service platform comprising: a global integration layer configured to enable an application to allow a user to access and use one or more services that are not natively supported by the application from within the application; a common control integration layer that provides a control configured to be hosted by the application, the control configured to be populated with one or more services that the application natively supports as well as the one or more services that are not natively supported by the application; and a custom integration layer that provides a set of Application Programming Interfaces (APIs) that can be used by the application to customize a user interface for integration of at least one service that the application natively supports and at least one service that is not natively supported by the application in accordance with the control; the user interface configured to receive a selection of a service and display a preview of the selected service by displaying content from a web address associated with the selected service, the selected service utilizing a declarative model that includes at least a display tag that provides a name of the selected service and a preview tag that provides the web address of the selected service.