This is tiny service which will periodically sync all of the locations in your upcoming Google Calendar to a contact in your Google Contacts.
why is this useful? Your contacts are likely synced to your phone. If your phone syncs with your car's navigation system, then the contact produced will show up, giving you an easy way to navigate to the locations in your calendar.
how does it work? First you select one of your calenders, then this service reads all of the upcoming appointments and geocodes the locations found. A vCard is created containing all of the addresses, along with a note summarizing your upcoming appointments. If you enable syncing, the process will be automatically repeated every few hours.
is this safe? Whenever granting permissions to your account, read the OAuth dialog carefully because it details exactly what you are granting access to. This service requires read permissions to your calendar, and write permissions to your contacts data. If you are ever concerned, you can revoke the access grant from your Google security settings.
still curious? Start by logging in and granting access to your calendar/contacts.