The science kits at The Young Scientists Club's Online Store have been recommended by some of the folks on the Sonlight forums. Both the "Young Scientist" Series and the "Magic School Bus" series look great. The Young Scientist series can be bought 3 kits in a set, or as a monthly or semi-monthly subscription. There is also an online "clubhouse" for kids. When we are ready for more science experiments, I definitely want to look into this further.