Serial Keyboard?

So I thought something like this might exist but I don't see one anywhere, hoping I don't have to roll my own.

What I would like is a keyboard that when I press A sends A to the serial port on the arduino. No screen needed or anything. I just want to send keystrokes to the arduino as though it was coming from a serial program.

Bonus points for it being small.

Anyone know of anything like this? My googling didn't return much other than ps/2 keyboards.

PS/2 is a serial interface. Given that you find a particular serial keyboard unacceptable you are going to have to clarify what you mean by "serial keyboard". Or explain why a PS/2 keyboard is unacceptable.