I tried the business card one, some origami ones and some other mediums (I had cut one from plastic) but they all were either too involved to recreate midair or not sturdy enough to hold the thing at the right angle.
I happened to have a hotel room key in my shirt pocket and mangled it into something that I now find myself dependent upon for my iphone holding needs. I like the fact that I can reuse something for another purpose and hey, they're free! It works well in coach as well as first class and haven't hit any turbulence rough enough to unsettle it. :D
Quick little update: Lots of emails and feedback on this little concept! I've added some bends to accomodate my new blacberry, I mainly use that as a stand at work . I see others have added bends as well as well as even making a nice dock! awesome.
Honestly, I know it's really simplistic, but sometimes those are the best ideas. I have used these on every one of my flights for my iphone while watching movies and I tell you it's the best traveling stand, because it's handy, easily replaceable and basically free!