WordBrain - Each level is a puzzle, where you are challenged to find a number of specific words!
Cold Turkey - Cold Turkey is a free productivity program that you can use to temporarily block distractions so that you can get your work done!
Hexic Link - Hexic Link is an Addictive, Puzzle, and Single-player video game developed and published by ThinkCube Inc.
Stay Focused - More suitable with Google Chrome, this service enables you ensure you do not waste precious time on updating Facebook status or chatting with people.
Board Defenders - Puzzel games based on the chess rules
Freedom.to - Freedom is a productivity hack that lets you block apps, websites or the entire Internet on iPhones, iPads, Windows and Mac computers.