I've been using Lumosity for some time now and I like it a lot. I use it weekly and I always like finding new games to play. Whether you believe in the whole neuroplasticity thing or not, it is proven that puzzles and games of logic improve many aspects of your cognitive abilities. In other words, they make you smarter.
Lumosity is basically a web service for brain training through quick mini games. The games focus on memory, puzzle solving, reaction time, logic and other similar type of games
So instead of playing Starcraft, or Candy Crush or some other bs game like that, I spend a little bit of time when I can playing one of these games. The one in this video is a fun one, called: Speed Pack. Watch it and you'll see what it's all about.