From updating your MySpace page to transferring money between bank accounts, all manner of online activities require you to log in with a username and password. Proper security practice demands that you make each password different and use random combinations of characters, like "f*&WQb28." But in the real world, you can't remember those, so you wind up either writing down your strong passwords on a Post-it you hide in your desk drawer, or you use "rosebud" for every site. What you need is a password manager—a tool that remembers and replays all your complex passwords for you. That way you need memorize only one complicated password—the one that opens the password manager.

Two of the tools described here don't even require that master password. Both UPEK Eikon To Go Digital Privacy Manager and DigitalPersona Personal 4.0 use your fingerprint to unlock password data. And they both include a number of bonus features, such as the ability to perform your Windows log-in and start file encryption by swiping one of your digits across a fingerprint reader.

All the password managers I've reviewed can capture username and password credentials as you log in to ordinary secure Web sites. Differences start to show up when you encounter the complex multipage log-in procedures used by more and more banks. 1-Click handles these beautifully by capturing every stage of the log-in process. ID Vault has a database of log-in techniques for thousands of financial sites, but can't learn new ones. LastPass, Eikon, and DigitalPersona handle this situation by capturing all data fields on each page when you tell them to. As for RoboForm, Identity Safe, and Large Software, well, they just can't capture the complex log-ins.

When you sign up for access to a new secure site, some password managers don't memorize the new credentials until you actually log in for the first time. RoboForm, LastPass, and 1-Click are smarter than the rest. They offer to generate a random strong password for your new account and will also memorize the log-in information at the time you create the account—that's handy!

All of these tools support Internet Explorer, and all except ID Vault support Firefox. For most, browser support ends there. RoboForm supports IE-related browsers like MSN and AOL as well as Firefox-related browsers like Mozilla, SeaMonkey, and Flock. Large Software is compatible with 20-odd common and uncommon browsers. But LastPass takes the flexibility prize: You can use it in any browser that supports JavaScript and bookmarklets.

Having all your passwords stored in a password manager pretty much ensures that you won't remember them yourself. That can be trouble if you're not at the computer where the password manager is installed. RoboForm and 1-Click solve this problem by offering portable versions as a separate purchase. Large Software will automatically generate a portable version at no charge. LastPass offers the most options for mobility: Because its stores your encrypted password data online, you can access the information from any browser. There's also an option to install LastPass along with Portable Firefox on a USB key for use on any computer. And if you just need to view the data off-line, LastPass Pocket handles that task.

How much do you have to pay for this convenience? The fingerprint-based products cost a little more, since you're buying hardware as well as software. Most of the rest are in the $30 to $35 range, though ID Vault costs $49.95 each year. The best deal of all, though, is LastPass. It's our Editors' Choice, with more features than the rest—and it's free.—Next: Products In This Roundup >