Inflatables are an obvious choice for space vehicles and satellites, a small sized payload than can be inflated once up, yet for some reason they aren't the norm.The first passive communications satellites were inflatable spheres, such as the Echo series, which mylar was developed for, and early prototypes for space stations were inflatable. More recently, funding for the inflatable replacement for the habitat unit on the space station was cancelled and a private company Bigelow Aerospace is now the pioneer in the field, having successfully launched an inflatable unit.My favorite in this list, however, is the grid sphere satellite which replaced the Echo ones which didn't stay up long becuase the suns heat would deform them and slow them down. A helium inflated plastic balloon expanded a signal reflecting hollow geodesic mesh, with the plastic then dissolving under the suns rays. The mesh could then stay up for 11 years or so.