I haven't seen many iPhone tripod adaptors (except for those on instructables), and I wanted to make my own. I was in a hurry, and needed something sturdy, simple, and easy to make. I recalled the robust packaging that my iPhone came in, and at that very moment, I knew what I was going to use.
This is an adaptor made from the plate that the iphone rests on in its packaging. This project also uses electrical tape, a rubber band, hot glue, and a 1/4" female screw (*term?) from an old webcam. If you desire to make a similar "adaptor" for your phone, yet don't have any old webcams lying around, then you might find a fitting bolt at your local hardware store.
When I look back at this adaptor, I feel 100% satisfied. It took less than 10 minutes to make. It works perfectly for my purposes, and the versatility of my Gorillapod makes it even better. You might also notice that my design does not block the mic located next to the charging/data transfer socket.