A colleague at work turned me on to KeePassX -- well, two years ago. But I only started using recently when I saw him juggle a listful of passwords painlessly. On the other hand, I was struggling with those "change me every 90 days and don't use one you've used before" situations.
KeePassX manages passwords, and can generate and then store them. You can even make an Ultra-Secret printout of your passwords.
Pastoral note: a good thing to be added in a death file.
Available for Linux, Windows and Mac OS machines. Ubuntu Linux users can get it from the Ubuntu Software Center -- or you can apt-get it if that's how you roll.