If you have one of these babies, use it.
At Walt Disney World, you are going to leave your stroller outside at most buildings. And while it's a pretty safe bet that you'll find your stroller fairly close to where you left it, be sure to put your phone number somewhere on it. This way, if someone accidentally takes your stroller and then leaves it elsewhere, a Cast Member can reach you. I have used my label maker to put my last name and phone number on the frame of the strollers I have taken to the World. This also does double-duty of marking them for gate check (you do have your contact information on things you leave with an airline, right??) And don't worry about the label machine, a piece of tape and a Sharpie will work just fine.