I'm a happy owner of a Nintendo DS and one of my favorite games for it is Brain Age, which lets you do a variety of small puzzles and arithmetic to hone your mental fitness. If you don't feel like shelling out $130 for Nintendo's hardware, there's Lumosity from Lumos Labs, a Web service that offers a similar multitude of small mental exercises that run right in your browser and are actually really fun.
Lumosity comes with nearly a dozen "games" to play, with each one working out a different aspect of your mental prowess, including memory, cognitive control, processing speed, and the all-important attention. As you play, your scores are tracked and grouped together in an progress chart that you can dig into and try to figure out what's been improving--or what needs some work. Games will also let you know when you haven't performed as well as you usually do by tracking your historical performance.
Earlier today I started out my brain-training session with a game called Bird Watching. It's meant to track your attention, but it ends up being a very strange mashup of Nintendo's Duck Hunt meets hangman, where the goal is to not only shoot a picture of the bird that pops up on the screen for half a second, but also remember the letter that flashes in the center of the screen. These letters begin to fill out the name of the bird, and it's your job to guess before you've captured all the letters--a process that (hopefully) uses a number of parts of your brain.
Following bird watching my heart rate went up about 30 beats with Speed Match, a game that pits you against a variety of symbols in the hopes of figuring out whether the symbol you're looking at is the same one that came before. To navigate you simply have to use your keyboard's arrow keys. It's quite a bit more fun than Word Bubbles, another game that makes you type words that start with the three letters they give you. Scrabulous players will mop the floor with this one.
The other games were not nearly as memorable, including one that has you type in the direction of the middle bird seen in flying formations (apparently to test reaction time), as well as a mine-sweeper-like game that has you navigate a garden to get to a flower while avoiding space aliens.
The real hook of the service is the stats tracking, which will keep track of your mental scores indefinitely and do analysis of your cognitive prowess based on how you've been scoring in each title. Like Nintendo's Brain Age series, it gives you some of this information in a four-way chart, as well as plenty of line charts that hopefully are getting better each day.
At $80 a year, Lumosity isn't exactly cheap when compared with Nintendo's Brain Age series, but you don't need to buy any extra hardware and the creators continue to add new games. There's also a two-week free trial you can play without entering any credit card information.