http://www.discoverthis.comThis site has many different gifts that will help educate your children while they entertain them. Pretty cool site even for adults!
Examples:
Smithsonian MicroChem XM5000 Chemistry set that provides over 1,500 experiments.
Various planetarium and solar system models.
Hovercraft educational science kit.
Kite kits that teach the dynamics of building kites and how they work.
Various kits on electronics and magnetism.
Digital microscope that you can connect to your computer.
Multiple robotics kis that even include a robotic arm trainer that can be controled by a computer.
Earth science project kits.
OWI Tripple action solar car kit that demonstrates solar power via a solar power toy car.
Even a build your own hydrogen fuel cell car along with solar power car.