INDIVIDUAL - I created a set of grade-level specific music flash cards that are color-coded for each of the grades I teach (1st - 5th). They are in the front of the room and separated into individual bins labeled 1st, 2nd, 3rd, 4th, and 5th. When a student answers a question correctly or assists me or another student with a lesson, they can go select a card. At the end of class, they hand the card back to me for a skittle or a sticker. If there is time at the end of class, I'll ask those students who have cards to come up to the front and share the musical term/definition on their card with the rest of the class.
WHOLE-CLASS - I have a clip chart in the front of the room with every classroom teacher's name on it. The chart is color-coded as follows:
Blue - Standing Ovation
Light Blue - Bravo
Green - Round of Applause
Yellow - 2 thumbs up
Orange - 1 thumb up / 1 thumb down
Red - 2 thumbs down
Purple - Award Winning
All classes start the year out on "Yellow - 2 thumbs up". During each class period, depending on class-wide behavior, their clip moves up or down. At the end of each quarter (9 weeks), the classes whose clips are on "Purple - Award Winning", get a prize or game day. All clips move back to yellow at the beginning of the next quarter.