Mandalynn posted a link to this interesting online game-thing on her blog, Hugs and Hissyfits, and I took the test. Apparently my brain is a youthful and spry 27 years old!
To play, click on the link and then press Start. There will be a countdown from 3, and then numbers will flash up on the screen. Try to memorize them. They will disappear and be replaced by circles. Click on the circles in order from the smallest to the largest number. You'll repeat the process ten times, and then the site will tell you the "age" of your brain. Let me know your brain-age in the comments!