The present invention relates to interactive advertising which permits a vendor to be provided with feedback from interested consumers. A publically accessible data transfer system is also disclosed which permits members of the public equipped with personal digital assistants (PDA) (45) to receive and transmit data via a transponder (9) located on outdoor advertising signs (1) or similar locations. The transponder (9) includes a cache memory (54) and is able to communicate with a server (42) to upload and download data. A system of product data dissemination and a commercial premises data transfer system are also disclosed.
