Brain Age for the Nintendo DS ($20) is a videogame masquerading as a brain-training tool. The exercises include rapid-fire math, counting syllables, reading aloud, and even drawing pictures from memory. The friendly bobbing head of Japanese neuroscientist Dr. Ryuta Kawashima explains what each exercise is good for (mostly stimulating your prefrontal cortex) while cheery music plays. Too bad this stuff doesn’t really make you smarter. But it is fun, and playing with a friend and comparing notes makes for great conversation and friendly competition.