This is one of my favorite things to do for marketing!
I will go to a vet's office and take pictures of their pets (usually dogs, sometimes other things!). From those pictures, I will make a canvas or metal wall display and hang it in their lobby and/or exam rooms.
This is great marketing for me because it lets me get my work in front of all of their clients. It's also a great deal for them because they get thousands of dollars worth of artwork in their clinic for free, and also a big ol' picture of their own dog to stare at all day.