Systems and methods are provided to deliver business information to users through users' online address books. Data aggregation servers associate individual businesses with one or more unique identifiers. The data aggregation servers collect, store and periodically update business information relating to individual businesses from a variety of sources, such as the businesses themselves and third party sources, such as online publications and message boards. The data aggregation servers store the information in association with the unique identifier. Electronic address book applications hosted on user devices store address book entries for individual businesses in local address book databases. The entries for each business include the unique identifier, and the online address book applications use the unique identifier to retrieve business information relating to individual businesses from the data aggregation servers.