OSXClock is a big, beautiful clock for you mac. Key features include a productivity log -- allowing you to track how much time you spend using different apps -- a timer, an alarm, and a zoomable display.
OSXClock can be used to quickly set break times from desk work, display a countdown or project a massive clock on an external display. For example, instructors could find it useful in their classes when giving timed tests. Freelance creative professionals can use OSXClock's Productivity Log to measure how much time they spend using various apps.
Spend a minute watching OSXClock in action here: OSXClock on YouTube
* Please note that some features described above are not available in the demo version.