How Can I Find Out My Husbands Password For Facebook, Gmail, Google Mail, And Hotmail?

You can't.  But if you have lots of email addresses for yourself and you forget your password to one, and can't remember which default address you used you can go to the log in page, and click "forgot password".  When it comes up on hotmail that you have a choice between emailing or answering a question, choose to answer the security question.  Chances are that you will know the answer to the security question.
Then you can get into your account, change the password and change the default email address.
Also, most people have their accounts linked.  Once you gain access to one, you will probably be able to get to another through the first one.  Once you enter another, change the password and default email again on your other account.

Good luck.