I created this small tutorial for those who don´t know this technique.
If you master it, it is fun to do your own 3D photos. All you need to do is to take two pictures of the same scene with an offset of about eye distance. For things that are far away you can increase the distance. Also works with video.
Impressive 3D images I stumbled upon recently: yowayowacamera.com/
Prepared for parallel and cross eye viewing.