Learn languages!

This is an excellent article from Psyche on approaching language learning as an autodidact. 

Kids Web Japan

Kids Web Japan offers simple Japanese lessons

Spanish for Kids

Spanish for Kids (free lessons) - up to grade 4

Learner's TV

Learner's TV: "This is a comprehensive site providing thousands of downloadable Video lectures, Live Online Tests,etc in the fields of Biology, Physics, Chemistry, Mathematics, Computer Science, Engineering, Medicine, Management and Accounting, Dentistry, Nursing, Psychology, History, Language Training, Literature, Law etc FREE to its visitors."

This site sounds amazing; I've not tried it yet, but hope it's as good as it sounds.

FactMonster's Writing Skills site

For kids: learn different types of writing as well as spelling and grammar.

FrenchtasticPeople

Learn French for free at FrenchtasticPeople.

Learn American Sign Language - for free!

ASL (American Sign Language) University

Very cool...I've always wanted to learn, and the kids don't like the singing ASL program on PBS. ;)

100+ Language Learning Sites

I've not tried any of the links out, but the page looks intriguing: http://www.c4lpt.co.uk/Showcase/100langlearning.html