At first glance, the N91 appears to be a full-featured MP3 player—with dedicated music keys, prominent volume controls, a 3.5-millimeter stereo headphone jack, an FM tuner and a USB port. Only when you slide the faceplate down to reveal the keypad do you recognize it as a phone. Drag and drop music (MP3, WMA, AAC and M4A files) onto its four-gigabyte hard drive, then create playlists directly on the phone. $700