http://www.coderholic.com/10-more-puzzle-websites-to-sharpen-your-programming-skills/
http://sixrevisions.com/resources/10-puzzle-websites-to-sharpen-your-programming-skills/
http://repeatgeek.com/technical/17-websites-for-sharing-programming-knowledge/

Look good fit in small places - http://www.mr-sport.com.tw/post/exercise-in-office-resistance-band.html

Quite fun - http://java67.blogspot.com.au/2015/08/how-to-swap-two-integers-without-using.html