Designed to be the world's most secure flash drive, the IronKey employs military-grade AES hardware-based encryption using its IronKey Cryptochip. The encryption keys are stored on the drive itself and your password is required in conjunction with the keys to access and decrypt files. If you forget your password, you may be in trouble; after ten consecutive failed password attempts, the IronKey self-destructs (internally) and erases everything on the drive using "flash-trash" technology that physically overwrites every byte, making the data completely unrecoverable.
The hardware encryption is one aspect of the IronKey, but the online component is another. When you log in to the IronKey website (which again requires both your password and your IronKey to be physically plugged in to your machine), you can activate their secure web-browsing service which turns FireFox into a malware-protected, "stealth surfing" application. Other security-nut features include a "potting" technique that fills the innards of the key with black goo, waterproofing it past military standards and preventing hardware crypto-analysis. $79 will get you 1GB of peace of mind, but the biggest option is the 4GB drive for $149. [IronKey via EverythingUSB]