Great maths games at SUMDOG ... http://www.sumdog.com as suggested by Tim Rylands.

Another great game found on Burnham School Blog (NZ)

Click here to play http://www.y8.com/games/Spiderman_2_Web_of_Words

Some trick challenges here

http://www.sporcle.com/games/g/common_english_words

Here's a simple site that gives you a fun way of checking out your knowledge of circuits and electricity. As so often the site was flagged up on www.timrylands,com

Another game identified by Tim Rylands www.timrylands.com 

http://dsc.discovery.com/convergence/everestbeyond/game/gameplay/

Another game identified for us by Tim Rylands  www.timrylands.com

http://dsc.discovery.com/tv/alaska/frontier-alaska/frontier-alaska.html

I think you might like this game.

http://www.aurochs.org/games/cowthello/

Here are three more suggestions of games to enjoy on-line and learn some maths at the same time.

http://www.coolmath-games.com/0-b-cubed/index.html

http://www.coolmath-games.com/0-phit/index.html

http://www.coolmath-games.com/0-rolling-hero/index.html

Here are a couple of games for younger visitors...

CLICK BELOW TO PLAY

http://www.coolmath-games.com/0-series-boombot.html

CLICK BELOW TO PLAY

http://www.coolmath-games.com/0-mazerace2/index.html

Captain Bethan has spent ages seeking out her favourite games on Cool Math ... a site we picked up from one of the Kiwi  schools (World Champions). 

CLICK BELOW TO PLAY

http://www.coolmath-games.com/0-rotate-and-roll-players-pack/index.html