This technology concerns, in one aspect, using a person's social network graph data as a virtual visual cortex—taking image input from a smartphone or the like, and processing it with the graph data to yield a personalized form of processing based on the imagery. The user's network graph data is typically updated by such processing—providing a form of virtual image memory that can influence future social network behavior. In another aspect, the technology concerns identifying content (e.g., audio) by both fingerprint-based and watermark-based techniques, and arrangements employing such identification data. A great number of other features and arrangements are also detailed.