We are heavy users of Google Apps (Gmail, Google Docs, Google Talk)
and developed a task and project management application for them!

Manymoon is like Basecamp and Sharepoint for Google Docs.

Manymoon is free and you can sign-up here:

http://www.manymoon.com

Some of Manymoon's features:
* Private and Shared To Do List.
* Attach Google Docs to tasks and projects.
* Create a task or project, attach a Google Doc and it is
automatically shared with the people in that task or project.
* Forward emails (Gmail) to Manymoon and they will be converted into
tasks.
* Create projects and milestones. Attach Google Docs to your projects.
* Works with co-workers, customers and partners.

We have received great feedback from our customers and think you will
find Manymoon to be very useful. Any feedback or feature suggestions
are appreciated.

Thanks!