I have seen more than a few weird clocks in my day and most of them had to do with waking people up who tend to oversleep. I had a clock when I was a kid that you had to throw to turn the alarm off. My mom took it away after I broke some pictures in my room and used my brother's head as a target a few times. Ponoko has a line of clock like devices that you have to manually change the time on.
I guess these things could keep you busy, but really, they are weird. One of the devices is a will return clock that is like those that you see on the door at the some stores when they close for lunch. It is cooler than those round plastic clocks with the rotating arms are for sure.
I guess I could also see it being useful to teach kids how to tell time or something, but really a clock with hands is better suited for that. The things are expensive too with prices starting at $80 and going up to $115.