I have been addicted to
http://www.khanacademy.org/ for the last several months now.
Originally I wanted to help out my nephew with some math tutoring resources, but I found myself revising my own meager math skills, now I am determined to master calculus (and hopefully inspire my nephew to do the same).
Doing a forum search I can see other MMM'ers have been praising the glory of free education resources online including the Khan Academy in the other MMM forum sub-Categories.
In case it is missed in other threads. I thought I would throw in a topic post in Reader Recommendations, so parents and life long learners don't miss a great oppurtunity to pick up free world class math tutoring (and a variety of growing subjects) online.
PS. The metrics resources available (for students and coaches/teachers) are impresive enough alone to check out, so as to see how well and simpley they have been implemented to help track students' progress.