Brain Gym - description from Softdepia.com:
Your brain is much like your muscles. It needs to be trained, as muscles. Of course your life gives you pretty much of such training, but as with muscles to do your best you have to train different activities of your brain. Brain Gym is a pack of four popular mind games for your Pocket PC or Windows CE unit. With the Brain Gym pack you have your own brain training machine in your pocket.
Brain Gym is a "Free to try" program. You can download and try it for an evaluation period.