The other day, one of my co-workers walked up to me and had me login to a server. I pulled up the screen that asked for my username and password, where I promptly typed the username... and then stopped.
"What's wrong? Don't you remember your password?"
My simple reply: "I don't know my password."
So, if you're at like most people, you manage passwords in a few ways: your browser, and by using one (or maybe two) passwords. Not me.
I'm one of those people that has a lot of accounts on a lot of different systems. More accounts than most, easily close to or surpassing a hundred just for myself, and many of them must be changed on a fairly regular basis.
To cope with this, I use a password safe. It creates random passwords for me that I don't have to (necessarily) remember, and as a bonus helps me to keep track of where all my accounts are. Check out KeePass if you're interested (the article has a link to the application).