Re: propeller clock
I did the bob blick clock as well, only mine used a pic micro not an atmel, so I'm not much use to you.
The most difficult thing is the mechanics, getting power to the spinning board is hard, bobs original idea was too much for me, so I used another idea others have used, a coil on the stationary section and another close to it on the rotating section.
The other tricky thing is balancing the board so the whole lot doesnt shake, you can use some 3mm nuts bolts and washers for coarse adjustment and blobs of solder for fine.