Also known as a
USB key,
USB hard drive,
USB keychain hard drive or
USB diskette, this refers to a
solid state storage unit coupled to a
male USB
connector on a device the size of a
keychain.
While portable solid state memory is not a new technology (e.g. Sony's Memory Stick, CompactFlash, SmartMedia, etc.), most solid state memory modules are of a proprietary nature -- usually directly coupled to a particular brand of digital camera, and almost always requiring special hardware in order to interface with a PC.
However, USB keychains combine the stability and convieneince of solid state memory (no moving parts == Good Thing) with the ease and ubiquity of the non-propietary USB interface. Ultimately this technology may finally succeed where zip disks have fallen short: that is, replacing floppy disks as the common pluri-compatible method of data transfer between PC's.
At the time of this write-up, the following USB keychain products are available in capacities ranging from 8 to 128MB (including the powers of two in-between):
Personally, they are a bit pricey at this time, but when the price comes down I'll get myself a nice USB hub and a few of these. And if anybody figures out how to boot off of one of these babies, I don't think I'll ever own a FDD again . . .
Update! 3 Feb 2002: generic-man kindly informs me that "some BIOSes can boot to USB right now. I've heard tales of people using USB keys to do minimal Debian installs."