Made from the rubber-like soft plastic material found in cases such as NGP, Frequency ($25) is one of Incipio's newest designs for the fifth-generation iPod touch. Instead of the plain rear designs we're used to, this one has a neat graphic design resembling bars on a sound meter, mixing matte and glossy textures. It wraps all the way around the iPod, including protection for the Sleep/Wake and volume buttons while leaving cutouts for the rear…