Also, if your house burns down, you're screwed or something. You should keep them in an encrypted file that you also uploaded to your web server or email or something. And you should probably memorize a couple master passwords -- long, strong passwords for your secret key and your email.
Luckily one of my talents that happens to not be useless (unlike most of them...) is memorizing long strings of arbitrary digits. I could still get into most of my accounts. In any case, there's password recovery.
