<< I've seen a pic of this soemwhere before, but cant find the product.. it was in the shape of a cassette tape.. and u put mp3's in it.. to play in a casette player... >>
Could you please be just a little more vague? If you mean an adaptor from 1/8 inch stereo mini-jack to automotive cassette deck (ie the "car adaptor" of portable CD player fame) then you can get one at any radio shack. If you mean a stand-alone product that you copy MP3s to and then play in a cassette deck, then no such thing exists unless you are recording the audio onto cassette tape in realtime. EDIT: Ignore the previous sentence, I stand corrected by the post above mine.
ZV