(FORTUNE Magazine) – SOME YEARS AGO I wandered, unaccompanied, past the desk of the chairman of a multinational corporation and was amused to see his computer monitor all daisied up with yellow Post-it notes. SYSTEM USER ID: MRBIG, one note reminded him. PASSWORD: ELITE1. (MRBIG was not really his user name, but it was similarly egotistical.) Nearly a dozen other yellow stickers offered similar memory refreshers, each for a different online destination. Apparently Mr. Big was aware that it's important to choose passwords that combine letters and numbers, making them harder for intruders to guess, but had failed to grasp that posting those passwords on the computer wasn't such a hot idea.

By now the computer security department has probably bought Mr. Big his own fingerprint-based password-management device. These little biometric baubles, sold by such companies as Microsoft, American Power Conversion (APC), Sony, IBM, and others, cost $40 to $150 for stand-alone scanners, which resemble miniature computer mice, or--in a growing trend--little fingerprint-scanning portholes in desktop keyboards, mice, and laptops.

I've been testing a few of the fingerprint readers and generally give them two thumbs up (or at least an index finger up). While they can be used to prevent opportunistic snoops from gaining access to your Windows-based PC, and act as a fingerprint-based lock and key for encrypting specific files and folders, they're most useful for keeping your user ID and password information at your fingertips, literally. Instead of writing down all your secret combinations on sticky notes or trying to keep them in your head, you merely swipe your finger. After the initial setup process, which tends to be simple but tedious as you teach the device all your passcodes, the only thing you have to remember is not to pick your nose.

As corporate computer networks expand and the Internet becomes a routine venue for online shopping, banking, and information gathering, some of us have to remember dozens of different user names and passwords. Complicating the task, long strings of alphanumeric gibberish are more secure as passwords than easily remembered words. True, but sometimes I have a hard time remembering my own phone number, let alone a couple dozen different strings like MV8y66_XQp2^3. On top of that, we know that it's also a good idea to change all those passwords periodically--every few weeks or months, depending on one's level of paranoia.

My favorite password manager for Windows-based PCs is the APC Biopod, a pleasant surprise, because at $50 it is also one of the least expensive units I tested. The Biopod resembles a pinky-sized USB computer mouse with a glass sunroof and a six-foot tail. The long tail makes it convenient to place the scanner anywhere on the desktop but also makes it less than ideal for tossing in a computer bag for road trips. (For those who travel frequently, several laptops have built-in fingerprint readers, including the excellent IBM ThinkPad T42.) The Biopod makes it easy to "enroll" up to 20 fingers, more than sufficient for most families or office workgroups. Once the fingerprints are registered, the boring part begins: You have to visit each and every password-protected site you use, log on in the normal fashion, and then click a "remember password" command for the Biopod. On subsequent visits, when the site asks for a user ID and password, all you have to do is give it the finger. Similarly, if you want to encrypt, say, the document listing your New Year's resolutions, just right-click on the file icon, and Biopod will lock it, with your fingerprint as the only key. Just be careful: If you uninstall the Biopod and haven't made an unencrypted backup copy of the file, you won't be able to open it again. In my tests the Biopod worked with the Firefox browser as well as with Microsoft's Internet Explorer.

Microsoft's own Fingerprint Reader is even cheaper (around $40 at the discount stores) and also did a good job managing my passwords, but only if I used Internet Explorer to visit my log-on sites. That's no problem for people who live in a Microsoft world, but it's a deal breaker for those of us who use Internet Explorer only when there's no other alternative. On the other hand, the kind of folks who store all their passwords and log-in information on sticky notes glued to the PC probably don't spend much time exploring alternative browsers like Firefox. Microsoft offers the Fingerprint Reader both as a stand-alone scanner, slightly larger than the Biopod and with a glowing red light, or built into a desktop keyboard and mouse bundle for about $85.

Given the security issues that pop up regularly with Internet Explorer, not to mention IE's lack of innovation recently, lots of people are switching to Firefox (free from mozilla.org) or other rival browsers. Don't hold your breath waiting for Microsoft to give a hand, let alone a finger, to the competition. While Apple fans are probably waiting for a biometric fingerprint adapter for their beloved iPod, in the meantime there's the Sony FIU-600/M Puppy Suite (list price: $160), which does all that the others do, while supporting Mac OS X. Back in the analog age people used to tie strings around their fingers to help them remember something. Now, thanks to biometric devices like the APC Biopod, all they need to remember is the finger itself.