I bought this on May 1st 2003 for €35.
It has 32MB storage, which appears as a standard disk device on Linux
The timepiece is by Citizen and the USB 1.1 storage by Toshiba.
It's supposed to be waterproof (DIN 8310).

I think this is quite elegant as it's the same size as
an ordinary watch, and no battery power is required
for the USB subsystem. The only problem I noticed is
that over time the USB connector gets a little grimey.

The watch came with one vfat partition,
but you can manipulate the disk as you want.
I have multiple disk (32MB) images for
various uses that don't have the same number
of partitions. Therefore to be able to
use partitions that are not present when
the watch was registered with the system
(i.e. after I dd a new image to /dev/sda),
I need to do blockdev --rereadpt /dev/sda
Of course you could just reattach the watch,
but the command is handier and useful to know.

The handiest way to backup the watch is
dd bs=32k if=/dev/sda | gzip > watch.gz