I forgot the password to my iTunes home shared library. I know I can set a new password in the iTunes prefs, but I do not want to update all my home devices to the new password! I cannot find the password in the keychain either.
Your Home-sharing password is your Apple ID password. It should exist in your keychain:
If this appears:
Type in your user account password and click allow. You should then see your Apple ID password in plaintext.