This is a superb maths games and activities site. Design an avatar and stroll around and choose what activities you would like to do in a range of maths topics. The games are great and the graphics are well designed and child-friendly.
http://ictmagic.wikispaces.com/Maths
This is a wonderfully simple maths quiz site with a good collection of activities for the 4 operations. Choose your category and get 10 randomly generated questions to answer.
http://ictmagic.wikispaces.com/Maths
This site has a great set of maths games that are sorted into different primary age groups. Practise multiplication, more/less than, decimals and much more. No sign in or registration needed.
http://ictmagic.wikispaces.com/Maths