A chance video on the TED website titled "Let's use video to reinvent education" led me to check it out again. It's still chock full of wonderful maths videos and now includes science and finance ones as well - over 2,100 free videos in fact. Maths covers everything from basic addition to algebra, geometry to derivatives. And its still free!
But even more impressive, a whole knowledge-map based system has been integrated into it.
You start wherever you want - right back at Addition 1 if you need to - and each point on the map has videos explaining that particular topic. Plus randomly generated exercises for the topic - if you answer 10 in a row correctly, it assumes you have mastered that topic and marks it as proficient (shown as blue on your knowledge map). You can go back and watch the video again at any point without stopping your answering streak.
Once proficient at a topic, it then suggests the next areas you might want to do - for example after Addition 1 (1 digit addition), it suggests Addition 2 (2 digit addition), Multiplication 0.5 or Subtraction 1 (1 digit subtraction).
I've also noticed that if you haven't covered something in a while, it suggests you review the topic to make sure you can still do it.
You can also earn badges and points as you go along, but I'm not really sure what that's used for. There are reports in the back section that you can see how you (or your student) are doing - I think you can assign exercises as well. It's been trialled in a US school district where they set watching the videos as homework, and then do the exercises in class so the teacher can help each child at their own level. Radical stuff!
We're also still using Mathletics (since we've paid for it!) - but Billy's interest in that has waned - and some topics on Skwirk. Khan Academy offers another approach and is a nice one to add into the mix.