Dood : The Puzzle Planet - A strategy puzzle game for the smart ones
LogicLike - Improve logical thinking through engaging brain games
PH Builds a Puzzle - A realtime, collaborative jigsaw puzzle.
JobFlare - Brain games for job seekers
Atomas - Simple rules, endless fun!
Dualnback.works - Dual N-back is a specific brain training exercise, that's been shown by research - it might improve fluid intelligence.