Similar to the design of a popular commercial iPhone stand, I drew this in SketchUp from scratch. Holds an iPhone 3g / 3gs in either landscape or portrait orientation. It can be slid up / down the phone to change the angle and seems to hold great. I also added a small hole to it so it can be tied on a keychain or anything.
Note: The two files are as follows. The 'large' file will work for an iPhone 3g / 3gs. It's the same as the 'small' file but scaled up about 25%. The 'small' file was my original design, but proved to be too small for an iPhone. It might work for an iPod touch, but I don't have mine to test it.
Note 2: The commercial version of this is rubberized so that it doesn't slide off the phone. I have a single layer of electrical tape in the slot section of mine to help it grip better. Seems to work great!
Note 3: The rounded short edge of this is printable (with regard to overhangs) on the small file, but dicey on the larger file. It works, but only if your tuning is really good.
Works fine at 20% infill. I printed mine raftless in black ABS, came out great.