16. The system of claim 13 , wherein: the search condition specifies one or more digital media items including one or more of a digital image, video stream, audio stream or text document; and generating the collection of data objects comprises identifying one or more categories of digital media associated with the specified digital media items, where the collection of data objects comprises tag objects representing the identified digital media categories.
13. A system comprising: a processor; a storage device coupled to the processor and configurable for storing instructions, which, when executed by the processor cause the processor to perform operations comprising: receiving a request for a plurality of data items, the request specifying a search condition; searching a data store comprising a plurality of data objects representing data items for data items satisfying the search condition, where the data objects comprising one or more media objects; one or more tag objects and one or more page objects, where: a media object represents an item of digital media and is an instantiation of a media object class; a tag object represents a category of digital media and is an instantiation of a tag object class and each media object can be associated with zero or more tag objects; and a page object defines a relationship between a tag object and a media object; generating a collection of data objects representing data items that satisfy the search condition; using an iterator to sequentially access the data items represented by the data objects in the collection; and providing the data items to a user interface.