UK's Advanced MP3 Players store offers the tiny Pebble MP3 player under its own brand.
The Pebble MP3 player measures 47x32x13mm and weighs 20g. It is small but not as small as the MobiBlu DAH-1500i. But maybe you want a more organic shape than the Pebble should be of interest to you.
Features of the Pebble include FM Tuner, FM recorder, 64x48px blue on black OLED display, MP3, WMA and ASF music file support, 40mW output, USB 2.0, 12 hour battery life, 3D Sound,
The 512MB Pebble sells for £79.00 (113.31 Euros) and the 1GB version sells for £99.00 (142 Euros). The Advanced MP3 Players Pebble sure fits nicely to the Motorola PEBL Mobile Phone.
More details on the Advanced MP3 Players site.