1. A system comprising: a server computing device comprising one or more processors; and a non-transitory computer-readable medium coupled to the server computing device and having instructions stored thereon which, when executed by the one or more processors, cause the one or more processors to perform server-side operations for distributing digital content for display across a network, the server-side operations comprising: serving one or more web page documents to a client computing device operated by a user, each document containing instructions for a browser application to perform client-side operations, comprising: displaying, within a web page of a plurality of web pages, a graphical representation of a content sharing interface of a first social networking service, the content sharing interface comprising a content input area to which user input can be received and being absent a distribution interface; receiving first user input to the content input area; in response to the first user input, automatically expanding the content sharing interface within the web page to provide an expanded content sharing interface, the expanded content sharing interface comprising an expanded content input area and the distribution interface; receiving second user input to the expanded content input area, the second user input comprising digital content that is to be distributed; in response to the second user input, i) identifying a summary of the digital content that is to be distributed and ii) populating the expanded content input area with the summary of the digital content that is to be distributed; receiving third user input to the distribution interface, the third user input indicating one or more contacts to which the digital content is to be distributed; identifying at least one contact of the one or more contacts that are to receive an email distribution of the digital content, and in response, providing a change control interface within the expanded content sharing interface; receiving fourth user input to the change control interface indicating i) one or more changes to the email distribution of the digital content and ii) one or more edits to the summary of the digital content; displaying one or more icons within the distribution interface, each icon of the one or more icons being a graphical representation of the one or more contacts; receiving fifth user input to the content sharing interface, the fifth user input comprising a user instruction to distribute the digital content; and in response to the fifth user input, transmitting a post data set to the server computing system, the post data set comprising digital content data and distribution data.