Online
Physics:
Fantastic Contraption Do you remember a game called The Incredible Machine? This is a flash-based game where you solve simple puzzles using a variety of provided tools (rotating wheels, rods, etc) Highly addictive.
Practical Chemistry Lots of chemistry experiments, searchable by topic and level.
Food Science Looking for practical application chemistry, specifically as it relates to cooking (and, eventually, cleaning). This may be a start.
Home’s Cool FoodChem Page A list of food-related chemistry experiments. Not bad for making a mess in the kitchen.
Geography
http://www.top50states.com/ All about the 50 states.
Typing
BBC Online Typing Tutor Just what it says.
Keyboarding Skills Recommended, not tried yet. (2/5/09)
Fingerjig How fast can you type?
Typershark this is on the PopCap site so if you just point your kid at it, they may not actually make it to the typing portion. Be warned.
Keymaster Game to reinforce keyboarding skills, not a typing tutor per se.