1. A system for managing activities in project management, comprising: at least one processor device; an activity sensor for collecting project activity data from user inputs and project task change event logs wherein activity data from user inputs comprises posting activity and deletions and activity data from project task change event logs comprises user input of operations on project tasks; a project model builder for creating a project model by integrating said activity data with project tasks; and a central repository for storing the created project model created by said model builder.