Digital signage networks are a newly emerging form of electronic advertising technology that is rapidly growing in popularity but has received little attention in e-commerce literature. In this paper we motivate the cost reduction and increased effectiveness of advertising that is displayed and managed using digital signage networks as opposed to traditional signage. We introduce a partially automated intermediary, namely the digital signage exchange,that forms a virtual marketplace for the purchase and sale of display time on the digital signage network. We present a concise representation for a customer?s order for display time on the digital signage network and an informal business transaction management model for the exchange. This model includes support for advance bulk purchase of blocks of display time. It can also make a counter-offer to the customer when an order cannot be completely fulfilled as requested.