On the advice of someone here we have started looking at Khan Academy for maths.
Well, what can I say... It is FAN-TAS-TIC!!! And it is FREE!!!!
(Looking on Google seemingly they get their money through (some large) donations.)
We started looking at videos, but I found them a bit verbose at times. Instead I/we find it much better to work through the practice sessions skipping the videos altogether (although we did find the introduction to fractions useful). My kids are working through the sections (second and third grade) and seem very engaged. Usually I try to keep the explaining to the bare minimum and let them get on with it. If there is a more difficult topic they can just keep practicing it and them move on. Who would have thought you can come up with so many different exercises for early maths... (OK, some do look a bit convoluted, but still :) )
At the moment we alternate between that and sumdog (or is it dogsum... I can never remember), but the skills required are very different, so I find that they complement each other nicely, at this level at least.
Anyway, highly recommended if you would like to stretch your child. And the good thing is that you can simply zip through the sections if something is too easy, or slow down if you find something more challenging.
AND IT IS FREE!!!!!! (There MUST be a catch...)
PS
NO affiliation WHATSOEVER ;) I am just enthused. I wish my kids found their school equally enthusing, but that is an altogether different kettle of fish.