The Polar Clock
The Polar Clock, from Pixel Breaker, version 3 is now out as a screen saver for Mac and Windows. It's also available as a Mac OS X Widget.
I don't know why, but I love this clock. I'm mesmerized watching the seconds going around. With a little practice, you can visualize the time. I won't say this is the best way to visualize the time, but it's definitely fascinating.