Random must have Small Open Source Eagle PCB

Hi,

I'm about to send a 5x5cm pcb board to manufacturing but I'm only using about 1x4 cm.
Currently, I don't need any other PCB on this board.

I have a "good" 38x50mm left, so what I'd like to know is if you have any "must have" small PCB that you use a lot?

Anything related to DSLR/Photography I'd be really interested. Optical slave trigger for flash?... or anything

I was thinking about making some SOIC breakout board, but there has to be something more "funny" then this.

I'm mostly looking for some Open Source eagle file to populate the rest of the board.

I don't care about parts or what not, I just want to fill that huge empty space instead of wasting it.

Thanks!

If nothing else comes to mind, try jewelry... http://arduino.cc/forum/index.php/topic,160459.msg1203036.html#msg1203036

I found something really nice :

I'll get 2 per boards.

I made a small simple Optical Flash trigger from this : Rudy's Rants: DIY Optical Slave trigger
It filled another 1x2 cm.

I'll probably make some funky art on the remaining space and see how it turns out.

Excellent.