Well I know this is a bit of a plug but we are all very proud of this site.
Today we launched the 3rd evolution of the Lipton Braintrain site. It is packed full of new games a new ranking system and the ability to challenge your friends through Facebook as well (here).
There is also a mobile site which is worth while a visit if you have a couple of spare minutes.
Check it out at: http://www.braintrain.com.au