I teach at a small private school. We have an employee, I don't even know exactly what her title is, but if you want anything, she does it for you. She is the most selfless person I have ever met, and she never let's anyone do something nice for her without her paying you back tenfold.
For my Day #1 act of kindness I picked up a pastry from her favorite bakery, and snuck it into her box with a little note that said "You are awesome!" It drove her crazy that she didn't know who it was from and that she couldn't repay them.