This link is to a youtube channel that was created by a high school in Ohio. They make music videos explaining math concepts. All of the songs are parodies of pop songs from the 90's until the present.
Geogebra is a geometry sketch pad that allows the user to create various shapes and figures which can be manipulated in order to see patterns and relationships that exist in Euclidean Geometry. You can graph functions and then manipulate the graph to see the impact it may have on the function's equation as well.