Lumosity

This is one of the most well-known brain training apps. Like most apps in this category, it uses various games and puzzles to work out your brain. Unlike most, they have their own in-house science team that works with other scientists, clinicians, and educators to see what their products can really do. One study from this collaboration found that 20 minutes of Lumosity, five days a week improved performance in visual attention and working memory. [free for five sessions; lumosity.com]