Embodiments of a location sharing network manager process are described. The process is executed on a server computer coupled to a plurality of mobile communication devices over a wireless network. Each mobile device is a location-aware mobile communication device. The process determines the geographic location of a mobile communication device operated by a user within an area, displays a map representation of the area around the mobile communication device on a graphical user interface of the mobile communication device, and superimposes on the map the respective locations of one or more other trusted users of mobile communication devices coupled to the mobile communication device over the network. An advertising platform manager provides tools for an advertiser to create and transmit relevant ad messages to a user based on specific location, time, and profile data of the user. Such location-based ad serving allows for the creation of ads that directly leverage a key component of the user's interaction with the mobile device in that messages can be tied directly to the location display of a product or service offered by the advertiser. The ad messages can be provided in the form of text or graphic messages, logos, display branding. Information related to time and location-sensitive promotional events can also be effectively broadcast to users in the form of alerts or coupons that encourage user to visit a location that may be near the user.