Math Baseball
A math problem game offering baseball swings (as part of an interactive game) as rewards for answering math problems correctly.
www.funbrain.com/math/   reviews

Who Wants to Win a Million Dollars - The Science Game
Answer 15 science and math questions to win one million (fake!) dollars!
education.jlab.org/million/   reviews

Q-Puzzle
Jigsaw puzzle based on affine transformations over finite fields. This is the main site of WIMS (WWW Interactive Mathematics Server): interactive exercises, online calculators and plotters, mathematical recreation and games ...
wims.unice.fr/wims/wims.cgi?session=45E5CC35&lang=en&module=U2/algebra/qpuzzle.en&cmd=intro   reviews