Yes, this product is actually called the “Ultimate Smallest MP3 Player”. It measures just 24 x 24 x 24mm and features 2GB of built-in memory for all your favorite tunes. Product page.
How small are we gonna get before we lose the thing under our fingernail? And what’s with the headphones being heavier than the device itself? Whoosh! Anyhoo, it’s got an in-built FM radio and handles MP3, WMA, ASF and WAV