A while ago I had an idea to make my own alarm clock, with a PIC, some 7 segment LEDs, and the dismembered head of Hello Kitty. I bought all the stuff, and found some code for the PIC, but never got around to it. So recently I decided to I'd buy a cheap alarm clock and mod it. Turns out, that's remarkably easy. I had been worried that an off-the shelf alarm clock might not be amenable to easy hacking, but the one I got was amazingly modular:
The obvious daughterboard on top is the switch board - not only does each switch have a big, obvious solder pad attaching it to that board, but the board itself is just hanging on with ribbon cable to the main board. So the switches should be easy enough to hack.
Also, the display is similarly hanging off the main board on some ribbon cable, and has mounting holes for screws on either side. So it can be moved and mounted pretty much anywhere.
So there are 3 basic stages: