Established and Good

1. www.ncetm.org.uk (Free to register and it has so many materials to support teachers delivering National Curriculum 2014)
2. www.mathsisfun.com/
3. www.nrich.maths.org
4. www.counton.org  (previously www.mathsyear2000.co.uk )
5. www.amathsdictionaryforkids.com
6. www.bbc.co.uk/schools/teachers
7. www.ictgames.com
8. www.bigbrainz.com (download the free version!)
9. www.10ticks.co.uk
10. www.mad4maths.com/

And what about...

www.mathforum.org/dr.math/  or www.plus.maths.org

Are there any others you would recommend? Email me, please!