Bear with us on this one because there are now so many different cases in these two familiar product families that even our own heads are spinning from all the variations -- each case is for the fourth-generation iPod touch. First, there's Microshield ($20), a simple clear plastic rear shell that's largely glossy with frosted accents, followed by Microshield Accent ($25), which adds an integrated ring of opaque colored rubber to the edge of the shell…
