Here are some that we have found useful.
The
Virtual Teacher Centre contains a wealth of useful resources and ideas across the curriculum. Use this web address http://vtc.ngfl.gov.uk and search mathematics / primary.
One part of this site that might be of interest deals with ‘The Role of Calculators in Primary Mathematics’. The article contains sound advice and 30 calculator activities related to clear learning objectives, questions to ask and what you might be looking for during the activity.
This part of the site is at the address http://curriculum.becta.org.uk/docserver.php?docid=2685
useful for resources and all the publications from the National Numeracy Strategy. www.standards.dfes.gov.uk/numeracy
is a lively site with many puzzles, games and areas where children can contribute on line. It also has links to other maths sites.
Find it at www.nrich.maths.org.uk

contains many resources including on line activities across the primary age range.
Find it at www.mathsyear2000.org/
At
Ambleside School they involve children in all parts of the process of designing
and creating content for their website. Many of the games have been designed by
or with children. .
http://ambleweb.digitalbrain.com/ambleweb/ambleweb/ambleweb/numeracy.htm

some areas of this site are Key stage 3 oriented but there is a useful section on investigations suitable for use with younger children and also some interesting puzzles.
atschool.eduweb.co.uk/ufa10/index.html
If
you need advice about problem solving and a range of activities have a look at
www.nzmaths.co.nz