I really like 1Passwd.
A simple utility that integrates with any browser, including my favourite, Omniweb, to provide strong and secure passwords online. The .Mac integration is also important for me.
Passwords are a constant problem for my students who use very obvious or easily guessable ones, (you'd be amazed at the amount of ones who use the word 'google') or come up with tortuous names that they forget a month later.
I usually recommend to them that they think of two passwords and use one or the other when online. I get them to think of something only they will remember, their first schoolteacher, or their grandfather's home, and to combine that with a date they will not forget.
1Password has made hopping around the web much simpler to do, logging in and out of different sites is simply a matter of choosing the relevant id and password from the pop up menu which is site appropriate. It can generate secure unguessable passwords, the ones that look like gobbledygook, which you don’t have to remember, they’re available in your browser bar.
The one drawback is using a different computer to access those sites, when 1Password won’t be available to you. It’s solid and secure and so easy to use, this is a minor drawback for me.