Systems and methods have been developed for displaying contextually relevant advertisements to users as media objects are being rendered. One or more data sources with contextual information for different portions of each media object are maintained. From this contextual information, keywords may be generated and used to locate contextually-related advertisements. The advertisements are selected based on contextual information about the media object in order to match or otherwise be contextually relevant with the media content being rendered. As the subject matter of the media object changes during rendering, different advertisements related to the new context are provided that replace the prior advertisement. The advertisements are displayed in an area that could be used for other purposes when the rendering device is not rendering media objects.