Here's a clever design: a whiteboard clock that erases your appointments as they happen. The lack of a minutes hand robs it of some of its usefulness, but the concept is still sound. [Il-Gu Cha via Make]
Couldn't you have a minute hand (and for that matter seconds) that was just above the surface of the clock, not erasing stuff?
Although on second thought I see a few problems with this:
- Your appointments have to be at exact hours, not twenty past or whatever.
- When the hour-hand starts erasing something, (like in the above picture) it can be hard to know from the other half of what you wrote, and what you're supposed to remember
- You can only plan for the coming twelve hours, not longer