Remember when transferring large files involved large e-mail attachments, oversized diskettes, or hooking one computer to another? Now you can carry your hard drive on a keychain. These new, tiny memory devices plug directly into a USB port. Download your data, and voilà! Music, documents, even video to go. Need to add to your data stash? No worries; these devices can be erased and used over and over.

DiskOnKey by M-Systems, $30 to $250 for 8MB to 256MB capacity
Pros: Most popular brand resold by major computer makers such as Dell, Compaq, and Sony (as Micro Vault). Only one with a built-in CPU, allowing security protection to reside on the unit.
Cons: Only up to 256MB as of this writing, although capacities up to 1GB are coming. Only newer models have KeySafe security feature.
Bottom Line: With so many resellers, it’s easy to find in a variety of colors and prices. Shop around for the best deal.
Thumbdrive Touch by Trek 2000, $229 for 128MB
Pros: ThumbDrive created the first device in this category and this new version uses your thumbprint as a security pass.
Cons: The Touch lacks the large-capacity sizes of 256MB and up that other ThumbDrive versions offer.
Bottom Line: If security is paramount, size can be overlooked. If big memory is your thing, try another ThumbDrive product.
USBDrive by JMTek, $25 to $1,000 for 16MB to 2GB capacity
Pros: Only keychain device to offer a giant 2GB version, as well as new weatherproof and bootable versions. Includes a USB cable.
Cons: Capacity comes at a price.
Bottom Line: Convenient cable, competitive pricing for smaller capacities, and the option of huge storage make this a good choice.