A network-based contact management system provides various features for assisting users in locating, and sharing information with, other users. The system provides a web-based user interface through which each may user create a personal data record, establish contact relationships with other users, and specify permissions for allowing such other users to view the user's own personal data. Users can preferably view the personal data records of their respective contacts via personal address books in accordance with the permissions granted by such contacts. A search feature enables each user to search for contacts of that user's own contacts to locate other users of interest. A crossing paths notification feature notifies users when their travel plans coincide with those of their contacts.