Mind Training Games Online

I have been having a go at Mindtree - http://www.shockwave.com/gamelanding/mindtree.jsp - which claims to keep your mind in shape by testing your abilities in four areas - logic, awareness, arithmetic, and memory. It's a bit of fun and may even be of benefit. Personally I've found that I'm reasonably good on the first three but my memory is terrible.

Anyone know of any other websites in a similar vein?