If you could turn one of your past unsuccessful idea into a great business, which one will you choose?

Maël l’higuinen ‏ @mael_lhiguinen: If you could turn into a great business one of your past unsuccess idea wich one will you choose ?


This business idea is still a good one i think: http://www.jamesaltucher.com/2011/05/an-idea-i-had-that-went-down-the-drain/