Many computer-based musicians now carry a USB memory stick as a matter of course - these things are great for quickly transferring large files between computers.
Typical high street models only offer a few gigabytes of space, though - if you're looking for a flash drive that will enable you to carry around even your most gargantuan projects, check out Corsair's new 64GB USB Flash Voyager.
As well as offering this massive storage capacity, the Voyager also benefits from having a rugged, waterproof casing, It's said to be suitable for backing up data and is bootable (so you can install operating systems and applications onto it).
The only downside is the price; at $250, the 64GB Voyager costs the same as a 120GB iPod Classic, though Apple's music player, of course, is hard disk- rather than flash-based.
More details are available at the Corsair website.