I'm not sure what grade you teach, but when I taught fourth grade, I'd put students' names on the board when they were caught doing something stellar. Getting your name ON the board was a goal. It was funny the first time the principal came in and saw a lot of names and started fussing the students out until she realized it was a GOOD thing. Her next response was, "Why don't I see all the names on the board?"
Brian-- I teach 6th-8th grade. That is a funny story about your principal! I'm sure she was excited that you were rewarding the positive instead of just writing kids up there for negative behaviors. Do you ever have problems with students acting good in front of you, then being a different type of student when you're not around?