IntelliGantt allows you to create complex project plans/gantt charts and upload these to your SharePoint/WSS Site. It will create the tasks associated with the project within SharePoint and assign the users. The project plan is visible from within the SharePoint site saving a fortune on MS Project Licenses!
Changes made in the SharePoint site and Visa-Versa will be reflected in the IntelliGantt software when the project is next syncronised. This way you could have one ‘Project Owner’ who creates the project plan and the project engineers will simply use the SharePoint site.
It works with both full MOSS and WSS and is really easy to use. They are currently offering a few different versions of the product – IntelliGantt Plus V3, IntelliGantt Beta V4 and an IntelliGantt add-in for MS Project.
Have a look at their website for more details – http://www.teamdirection.com/intelligantt/index.html