Maths Links -
Free math course, very comprehensive. Covers up to A-level including enrichment.

Has a UK version, highly recommended by many HEers

Maths through literature, recommended reading & curriculum available

Free downloads up to age 11

Girls will love this.

Interactive maths practice

Interactive games

Lots of resources for all ages

Cheaper to buy from Amazon or 3 for 2 in Smiths when on offer, but you can download sample pages and extra practice here to make sure your child likes the approach. Very back to basics, no coloured pages or cute cartoons.

Free downloadable maths for codebreakers. Surprisingly accessible and makes maths more fun for non-maths types too.

Free downloadable maths resources for 5 - 11 year olds

Games and fun. Very bright and jazzy. Could well appeal to maths haters! Olympiad for competitively minded in need of enrichment.

Maths games from the Plymouth maths people. Ideal for times when you need a break from maths but still want to do something educational.

Really good maths textbooks

Great ideas for learning number bonds (1+1 etc) Thanks to Laura.

Some free resources for this online maths programme by Carol Vorderman - quite pricey but looks good.

Online maths for 5-13 - again quite pricey.

On line maths - again, pay to use.

Secondary Maths to GCSE. Pay to subscribe but HE maths available. It has a tutorial scheme and on line marking.

Maths based round the space programme. Challenging but fun.

All sorts of maths games and resources. US site, but looks to be pre-school up to GCSE.

US maths site. Thanks to Tina Creed.
Maths and spelling. A bit clunky and temperamental if you are a member but if you/they aren't bothered about storing scores you can use it as a non-member. DD loves seeing that she is getting faster at answering because you get 1 minute for as many as you can do.