Golden Tickets and Mimikatz: Using Mimikatz, we can use the password information for the KRBTGT account to create forged Kerberos tickets (TGTs) that can then be used to request TGS tickets for any service on any computer in the domain.
Another one of my favorite features is the ability to use Mimikatz to implant skeleton keys using the misc module with the skeleton command, which will patch LSASS to enable the use of a master password for any valid domain user.