Abstract: A facility for identifying a location in a printed document is described. The facility obtains an image of the printed document, and extracts gestalt information from text occurring in the image of the printed document. The facility compares the extracted gestalt information to an index of documents and, based upon this comparison, identifies a document that includes the gestalt information.

Abstract: A facility for identifying a location in a printed document is described. The facility obtains an image of the printed document, and extracts gestalt information from text occurring in the image of the printed document. The facility compares the extracted gestalt information to an index of documents and, based upon this comparison, identifies a document that includes the gestalt information.

Abstract: Systems and methods for allowing communication between two or more proximate mobile computing devices. In one method a first device detects the presence of a second device. A signal is sent by a first device for requesting a comparison of the lists of media files. The signal can be sent to a second device (or to a server over a wireless network) and may include the list of media files associated with the first device. The second device sends a list of media files to the first device after receiving the signal. An alert is outputted if a list of media files associated with the first device is determined to be comparable to a list of media files associated with the second device based on one or more predefined parameters.

Abstract: Systems and methods for recording viewing of an advertisement on a mobile computing device. In an example method the mobile computing device initiates presentation of a digital content file having one or more associated advertisements, transmits from the mobile computing device at least one of an identifier for the presented digital content file or an identifier of the associated advertisement over a wireless network to a server, and updates an advertisement impression count at the server based on the transmitted digital content file identifier or associated advertisement identifier. The digital content file and associated one or more advertisement may be received from another mobile computing device. The mobile computing devices include cellular phones.

Abstract: Methods and apparatus to enable a distinction between “new” and “used” digital content and to enable a market in used digital content files between mobile phone terminals and an electronic store, securely, by means of a wireless telephony network and a server complex to handle contents right management, transaction reporting, inventory, content delivery, payment, and billing. A server receives a signal generated by a wireless user device that was sent over a wireless telephony network. The signal indicates an election for returning at least one previously purchased digital content item. The server deletes user rights for the at least one digital content item identified by the received signal and sends information to the user device that generated the signal. Access to the associated digital content item at the user device is removed according to the sent information.

Abstract: Systems and methods for securely performing digital commerce. A user device provides a first key and a random number to a server over a first network, encrypts the random number and a user identifier using the first key, and sends the encrypted information to the server via a second network. The server generates an encryption of the random number, the user identifier, and a second key using the first key. The user device receives, decrypts and stores the second key. If the user device wants digital content, the server encrypts the digital content using a digital content key and encrypts the digital content key using the second key. The user device receive the encrypted contents, decrypts the digital content key using the second key and decrypts the digital content using the decrypted digital content key. Digital content can be passed to other user devices.