Get current user password

You can't, and that's by design. Password is not stored; a hash is stored.

To support single signon, you need a single domain (for cookie propagation) and at least some shared tables.

You may use AES encryption module.
http://drupal.org/project/aes

This module can provide you with readable passwords. You will be able to designate roles with the ability to view other users passwords in plain text.

N.Mehrabany
Baruzh web design & programming