My Daytimer wallet, which was on the nightstand next to the bed, disappeared - coincidentally right after the cleaning woman came and went. While I didn't suspect her (known her for over 40 years!) I just couldn't figure out what happened to it. Then I remembered I had run the Roomba to pickup all the dog hair that accretes under the bed.
Turns out the Roomba apparently had kept knocking on the nightstand and finally knocked the wallet off. Then it must have pushed it to the far corner under the bed. It would probably still be there if I hadn't caught site of the reflection of pen in the flashlight beam.