Location-based services are provided in a communication system comprising at least a portion of at least one wireless network. In one aspect of the invention, one or more interested parties are permitted to bid on available opportunities for delivery of messages to mobile user devices, and delivery of at least one message to a given one of the mobile user devices is controlled based on user profile information and at least one received bid for a corresponding message delivery opportunity. The message delivery opportunities may be specified as combinations of two or more of a message category, a location for message delivery and a time for message delivery. For example, a given message delivery opportunity may be a category-location-time combination.