You have to cross your eyes until you see three images. The middle image is the one that will be in 3D. Let your eyes relax until the middle image comes into focus.
Some work, like the grass growing out of broken concrete, but most of them don't work for me such as the garden, the tunnel, and this (I can only kind of focus on three floating slices of pizza).
Hm, maybe I just have bad eyes (some of the photos without a vey distinct subject remain as 4 blurry images with the two middle refusing to become one). Nevertheless, the ones that work for me are absolutely stunning. Fantastic job.
om nom