After getting an iPhone 4s so I could have a good backup camera with me at all times, I wanted to make sure I didn't immediately break the thing. The Otter Box Defender case is about the best protection you can get against droppage, but it makes your phone much bigger. With most iPhone tripod mounts relying on your phone being naked (which is ridiculous), I looked for something that was affordable and could hold the girth of the iPhone+Defender goliath. After a bout of despair, I noticed the Defender came with a plastic holster that could be re-purposed as a tripod mount. Problem solved!
Otter Box holster (comes with Otter Box Defender)
1x 1/4" machine screw, 1 3/4" long
2x 1/4" washers
1x 1/4" coupling nut, 3/4" long
various drill bits
For camera rigs that may work well with your smartphone, check out the Table Dolly Junior, Trolley Dolly and Mini Camera Stabilizer.