Mac Platform: Intel
OS version: 10.8+
Processor type(s) & speed: Intel C2D +
RAM minimum: 512 MB
Video RAM: 512 MB
Link for more information: http://www.busymac.com/busycal/index.html
BusyCal's unique 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 supports iCloud, Exchange, Google Calendar, and other CalDAV servers, enabling you to sync and share your calendars 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 app on iOS.
Ps. Tested, registered and worked.