Bird droppings along the roof peaks always adds a lively touch.
as would birds or cats on the roof...
pillows or laundry hung out of open windows to dry/vent
cats dazing on windowsils
wares in crates piled up in front of stores
wall mounted mailboxes
oh did I mention cats yet? You could place some on the entrance doorsteps
Now did I ever glue cats to scenery? Nope all of my 3 dozen or so cats are individually based on 15mm bases

PS: how could I forget about crates with milk bottles?