Have you heard of Gonoodle?  It is an awesome free tool that is simple to use and provides short brain breaks (dancing, Zumba, etc.) for your students.  A cute cartoon character of your choice earns points for your class and "grows" as different activities are completed.  One thing I really like is that there is a "demo" class for you to experiment with first. 
Important note: some of the videos require access to YouTube