Hard to believe, but
this guy actually collects do not disturb signs from hotels around the world. From his site:
"Do Not Disturb" signs are often overlooked even though some are very attractive and original in design. I started collecting them quite by chance and it soon became an addicting hobby. Sadly, these signs may soon become a thing of the past as more and more hotels are replacing them with hi-tech electronic devices.
And I thought I had some strange hobbies!