A web based task list manager

 Nag is a web-based application built upon the Horde Application Framework
 which provides a simple, clean interface for managing online task lists (i.e.,
 todo lists). It also includes strong integration with the other Horde
 applications and allows users to share task lists or enable light-weight
 project management.
 .
 This package is part of Horde, a web application Framework written in PHP with
 modules like IMP (webmail), Turba (contacts), Kronolith (calendar), Nag (task
 list), Gollem (file manager), etc.