I am not sure if BusyCal is the same BusySync (if it is I apologise)
Update: I have been informed that BusyCal replaced BusySync. Therefore scroll down to my second answer.
Download the 30 day trial of BusyCal 2, and if you think its to your liking you can always purchase it afterwards.
It is described as:
An award winning calendar that provides powerful time-saving productivity tools in a friendly, personalized, easy-to-use package.
BusyCal's unique and powerful features include customizable calendar views, scrolling Month and Week views, an integrated Info Panel for quickly viewing and editing events, integrated To Dos that display in the calendar and carry-forward until completed, custom font sizes and styles, graphics, live weather feeds and moon phases, and a menu bar app for quick access to the current day's events and weather.
BusyCal takes full advantage of the latest features in Mountain Lion, including the Notification Center for displaying alerts and banners; and Application Sandboxing for safe computing. BusyCal is compatible with iCloud, Google Calendar, and other CalDAV servers, enabling you to sync and share your calendars through the cloud with other Macs running BusyCal or the built-in Calendar app on OS X, as well as iPhones and iPads running the built-in Calendar on iOS 6.
An application called Blotter
Available from: http://wireload.net/products/blotter/
The link below tells you about using Blotter with Google Calendar depending on which version of Mac OS you are running: