A free app in the App Store called Seene will help you create 3D photo scenes, using your iPhone's camera. The process is simple, requiring nothing more than a subject that stays still and a steady hand.
Upon downloading Seene from the App Store, you're guided through the creation process. Basically, you need to find a subject that will stay still long enough for you to see lots of the little green dots used by Seene to map out an object.
From there you press the shutter release and move your phone -- not just rotate it -- but move it around until all four sections overlaid on the screen are green as in the picture above.
Once you've covered all the corners of the photo, Seene will present you with your creation. You can move your iPhone around to view the different angles captured. If it's not quite good enough, restart the process, taking a different angle or approach to the subject.
After you've created the perfect Seene, upload it to the service and share it on Facebook or Twitter.