Command & Line - Google Services
GoogleCL is a small wrapper for Google services that makes them available on the command line. It currently supports Calendar, Docs, Contacts, Blogger, Finance, Picasa and YouTube. I only use it to manage calendar events though.
Adding a new calendar event is simple as:
google calendar add "Lunch with Jim at noon tomorrow"
GoogleCL is a cross-platform Python application. It is available through pip.
pip install googlecl