cupsanddowns is a game where one team tries to turn all the cups upside down and the other team tries to turn them right side up. At the end of the time, whoever has the most their way wins. Simple, inexpensive game that could bring a lot of energy.
Listening - Even though this says "listening game for adults", I think it would be great for the elementary classroom as well. It gives students the opportunity to strengthen listening skills as well as cooperation skills, plus it would be fun!