A useful addition game where users 'handwrite' the answers in the box. The intro page is in Japanese, but the activity is in English.
http://ictmagic.wikispaces.com/Maths
Valve, a game developer has released their hit game Portal for free with a series of educational resources targeted at teaching Senior Physics and Maths. Will be checking this one out over the holidays, but so far looks excellent.
"if you're looking for an entry point into the level of discourse within the Critical-Gaming Network, a place to start developing your critical-eye, or seeking a crash course in game design then here is where you start."