Ad hoc forums may be created and updated to enable users to easily share information, collaborate, track reading progress, coordinate events, and/or exchange other information related to reading of a book or other written work. The ad hoc forum may be accessible via a uniform resource locator (URL), which may be provided to users without requiring user registration and without a need for a dedicated reader device. A service provider may receive information from contemporaneous readers to update the forum, such as to update reading progress information, add messages, add comments, add annotations, and/or other add or modify other collaborative information. The service provider may exchange information with user devices of users via communication channels other than the forum, such as via email and/or text messages, as well as dedicated reader devices, while using this information to update the forum.