1. A method comprising: by a client computing device, identifying an available timeslot for displaying content on a screen of the client computing device; by the client computing device, notifying one or more applications on the client computing device of the available timeslot; by the client computing device, receiving from each of one or more of the applications a bid to fill the available timeslot with content associated with the application, wherein the bid: indicates the application; indicates a format of the content associated with the application; and provides at least a portion of the content associated with the application; by the client computing device, selecting one of the bids; and by the client computing device, displaying in the available timeslot on the screen of the client computing device the content associated with the selected bid with the format indicated by the selected bid.