Even though I've called it the “iPhone Tripod Mount” it could work with any phone.
The reason I made this is because all the tripod mounts I've seen expect that you don't have a case on your phone.
This one expects a rubberized grippy case, and uses that to make it more secure.
Done! See the blog post: http://rasterweb.net/raster/2012/06/12/iphone-tripod-mount/
I switched to a coupling nut, which solved the “regular” nut issues, but it was a bit too long, so I had to take a hacksaw to it. Stability is much increased though.
I just rebuilt it last night with better wood, but I've still got an issue with the mounting nut. I'll work on it…