Bang! Boing! Pop!

From site:  Anyone can use Bang! Boing! Pop!, though it is best-suited for students in grades 7-12 with no previous experience in physics. 

Bang! Boing! Pop! is designed for students to use at their own pace. Hypertext links the student through the physical concepts, including conservation, energy, linear momentum, and angular momentum. Students also have at their disposal a hypertext physics glossary in case they stumble upon new vocabulary. Java-enhanced applets allow for the student to interact with physical quantities, building intuition while still having fun. Short quizzes covering basic physics concepts also allow the student to monitor his/her progress.