I wouldn't mind having one of those LED message panels mounted on the refrigerator, or somewhere in the house, especially if it was very simple to change the message. It would be a fun way to leave a note for someone.
I know they are available, but that wouldn't go over to well either. My wife is very understanding about my interests, but only as long as they stay in the office or basement.

She has the back room full of sewing machines, fabric, and purses she's made, so it all balances out.