Not always do you get to work with wonderful client that know what they want, but i have. Skedul.In soon to be launched in production mode (currently in beta) is a simple yet great idea: have single place to create all your events at Once , select your google calendar, use your google contacts and you are done, all events are created, invitation sent, your calendar updated.
MongoDB – Can’t live without it , also used for session storage
Completely relies on OpenAuth , you have to login with your Google Account
Google Calendar API, Contacts API
Hosted on Heroku
Couple of screenshots :