Manymoon
Manymoon, recently acquired by Salesforce.com (CRM), is another project management player that integrates with Google Apps. Using Manymoon, workers can add project information to shared Google Calendars and attach Google Docs to tasks, projects and events. They can also access Manymoon within Google sites such as iGoogle or Google start page by using the Manymoon tasks gadget, which provides a good way to create, view and complete tasks without having to log in to Manymoon. Price: Standard plan is free for unlimited users, projects and tasks. Advanced features available starting at $19 per user, per month.

RapidTASK
The RapidTASK app aims to simplify the confusion of project management by allowing a project manager to create a "to do" list and sync the list with Google Apps e-mail contacts. RapidTASK, which integrates with Google Calendar and Gmail, then plugs the project manager into the shared tasks so he or she can see what team members are working on in real time.  Price: Free; premium account $5 per user, per month, enterprise account $25 per user, per month.