How to send secret messages, links and pictures (like David Petraeus should have...)

How to send secret messages, links and pictures (like David Petraeus should have...)

Here's my column about why smart people like David Petraeus do dumb things with email: 

http://www.computerworld.com/s/article/9233756/Why_smart_people_do_dumb_things_online

I also lists some services that keep your information secret when you want it to be. 

Do you or should you use any of these services?