Microsoft Dynamics GP encrypts its system and budget passwords in a way which cannot be decrypted. Or at least it did. DynDeveloper.com, in April, posted an article containing a stored procedure which would allow the passwords such as the system or budget passwords to be decrypted.
As well as the stored proc, the article also includes sample code which will return the decrypted system password.
Update: It turns out this isn’t new and was first posted about back in 2010 when it was misunderstood what this type of decryption would cover. It is system and budget passwords (which are both optional and often not used), not user passwords.