I have been looking for an online Productivity tool, tried many of them, and finally settled on Teambox. It’s easy to use, intuitive, and keeps correspondence, project and task lists in one place.
 
I wanted to find a tool that is easy to use. Teambox provides each project with its own task list, pages, and conversations tab. There is also an area for uploading filel. Tasks can be assigned to each team member; their status is visible to all team members. All tasks can be viewed either across all projects, by the individual project, or by the owner of the task.
 
There is a free version for up to three projects that offers up to 50MB storage.
 
Are you using productivity or collaboration tools? Which ones have you tried? Which one did you settle on and why?