Get Mail, Contacts, and Calendar on Windows Mobile
Set up Google Sync on Windows Mobile	Set up your Windows Mobile phone with Google Sync to access your Google Apps mail, contacts and calendars from your phone's native applications.
Google Sync Help Center	Find out more options and features of using Google Sync on Windows Mobile.

View Google Docs on Windows Mobile
Point your Windows Mobile browser to http://docs.google.com/a/your-domain.com/m	From here, you'll see a mobile version of your Docs list where you can view documents and spreadsheets. More about Google Docs mobile

What other Google Apps can you use on Windows Mobile? Visit Google's Windows Mobile Help Center.