How to unlock a locked account

With the native NET command:

    NET USER loginname /DOMAIN /ACTIVE:YES

or, if the password needs to be reset as well:

    NET USER loginname newpassword /DOMAIN /ACTIVE:YES

List all domains and workgroups in the network

With the native NET command:

    NET VIEW /DOMAIN

Is someone's account locked?

With the native NET command:

    NET USER loginname /DOMAIN | FIND /I "Account active"

The account is either locked ("Locked") or active ("Yes").

When did someone last change his password?

With the native NET command:

    NET USER loginname /DOMAIN | FIND /I "Password last set"

How do I reset someone's password?

With the native NET command:

    NET USER loginname newpassword /DOMAIN

With (native) Windows Server 2003 commands:

    DSQUERY USER -samid loginname | DSMOD USER -pwd newpassword

Note:

To prevent the new password from being displayed on screen replace it with an asterisk (*); you will then be prompted (twice) to type the new password "blindly".

What permissions does a user have on this directory?

One could use the previous command to check what permissions a user has on a certain directory.
However, sometimes SHOWACLS from the Window Server 2003 Resource Kit Tools is a better alternative:

    CD /D d:\directory2check
   SHOWACLS /U:domain\userid

What is the full name for this login name?

With the native NET command:

    NET USER loginname /DOMAIN | FIND /I " name "

With (native) Windows Server 2003 commands:

    DSQUERY USER -samid *loginname* | DSGET USER -samid -display

Note:

The NET command may seem more universal, because it requires neither Active Directory nor Windows Server 2003 commands, but it is language dependent! For non-English Windows you may need to modify FIND's search string.