Yes, the humble thimble is the most popular playing piece in the game of Monopoly. I would have said maybe the dog or the car, but it seems this is not the case. When Hasbro did a study to see which piece was most popular, it turned out to be the thimble, which is as it should be.
Wouldn't it be fun for each player to just use a different thimble? My bag of ceramic thimbles (above) would give plenty of choice.