What's a good solution to securing mail, voice, and other services when viewing a shared Google calendar?

For a shared Google Calendar, I want to block access to GMail, Google Voice, etc. I'm open to any web or desktop solution that allows sharing of the Google Calendar data without giving calendar users access to the other Google services for that Google account. I assume any external (i.e. non-Google) sol'n would involve syncing Google calendar, which is fine. Anyone know of a sol'n? Free is preferred, but will consider paying for something.