You too can scan (hack) your way to retirement (dismissal)

SoftPerfect Scans Networks From A USB Drive - Lifehacker Australia

Windows only: A good network scanner digs deep into any network it's pointed at and opens it up for you to get into. SoftPerfect Network Scanner does those things, can do them from a thumb drive, and is a good deal less intimidating than some other scanner apps out there.

Just make sure you read you're company policy on network and system usage - most organisations take a dim view of their employees scanning the network without permission (even if it is part of their role)!