The present invention relates to data transmission, and more particularly relates to use of extracted or calculated identifying data as proxies in transmission. One claim recites a method including: receiving identifying data and information from a handheld device, the identifying data having been calculated from audible portions or video portions of first content utilizing at least a programmed electronic processor housed within the handheld device, in which the handheld device comprises a media player for rendering audio or video content to a user of the handheld device, and the information comprises capabilities associated with the handheld device; with reference to a database, determining additional content, enhanced or improved relative to the first content, that is associated with: i) the identifying data, and ii) the information; and providing metadata associated with the additional content to the handheld device. These techniques could be advantageously applied to cell phones. Of course, other combinations and claims are also provided.