Very nicely done! I like the form factor and your choice of the peripheral devices added.
What is it about the display you are syncing to the 1 HZ clock?
The shield idea seems nice, and keeps it to a good size for an alarm clock. I guess you could even replace the Arduino with a "bare bones" Arduino before dedicating it as an alarm clock.
Hardware-wise I have no suggestions but if were me, I'd add an X10 "Firecracker" to turn on an appliance or light.
Software suggestions are of course a dime a dozen, but if you don't mind, consider . . .
- auto DST setting (the TimeLord lib will do this for you.)
- alarm only rings Mon-Friday
- RTTL wake up tunes using the Tone lib.
Again, nice piece of work. I'm sure it was fun to design and build. Looking forward to see how you case it.
John