You could fill a weather balloon full of helium, attach an iPhone, release it and let it float so high the iPhone films the curvature of the earth. After it bursts, retrieve the iPhone via GPS.

Some Boston students did it and got footage including the curvature of the earth and the deep black of space.

http://news.sky.com/story/1295234/science-students-launch-iphone-into-space

This is a picture their iPhone took clearly showing the earth is not flat.