Mathematics Enhancement Programme- free K-12 math curriculum, available at http://www.cimt.plymouth.ac.uk/projects/mep/default.htm and http://www.staidenshomeschool.com/files/freemathscurriculumprek.htm
50+ Free Online Games and Activities for Homeschool Students
Lesson Pathways is now FREE! Curriculum reviewer says: "We also like www.lessonpathways.com for history at least. I have not tried some of the other sections though I have the K science pathway laid out to try. It is unit studies style which makes it far less than ideal for [...]. It is kind of neat if you don't mind putting in the extra leg work to do it."