Multiplication.com: Great fun for times tables practice.
Try these games: Grand Prix, Granny Prix, penguin, tractor
Khan Academy: it's like youtube for math (and other subjects)
Math Magician: practice your facts http://resources.oswego.org/games/mathmagician/cathymath.html
http://www.ei.lehigh.edu/learners/energy/index.html Student Resources
Science Fair Information included on the Science Link, under the subpage: Science Fair