This is just a fun online math game that involves a variety of skills. The 7th and 8th graders I worked with this summer loved playing this game with extra time we had.
For those of you with iPhones, this is an AWESOME graphing calculator app! It has a full calculator, graphing capabilities, polynomial solvers, as well as a reference section with pictures, definitions and equations. This can be very useful for students (or teachers) without access to a full graphing calculator! ...And its free!