Greetings, brethren... Has anyone seen or had any experience with the handful of retro MP3 cassettes available on the market? These are units which a) look like cassettes, and b) can be used in cassette players but store music as MP3 files (they apparently can also be used as standalone players with a set of headphones...) I tend to use cassettes more than the MP3 via line in option with my vast collection of 3 boxes (soon to be 4 thanks to Roman ) and thought this might be a pretty cool option...