Here is a compiled list of 10 great tools for sys admins

1. NTFS Permissions Explorer

Using this MMC snap-in you can quickly visualize the user and group permissions of a local or remote folder or drive in a hierarchical format to help identify problems.

http://eprints.hud.ac.uk/9743/

2. Whois

Whois performs a lookup of the registration information of a given IP address or domain name.

http://technet.microsoft.com/en-gb/sysinternals/bb897435

3. Xirrus Wi-Fi Inspector

Wi-Fi Inspector is a powerful Wi-Fi management and troubleshooting tool that allows you to locate and verify Wi-Fi devices, detect rogue Access Points, troubleshoot connections, and search for Wi-Fi networks.

http://www.xirrus.com/library/wifitools.php

4. ShareEnum

ShareEnum allows you to scan and view the security settings of file shares on your network.

http://technet.microsoft.com/en-gb/sysinternals/bb897442

5. PipeList

PipeList displays a list of named pipes on your system, including the number of active instances and the instance threshold.

http://technet.microsoft.com/en-gb/sysinternals/dd581625

6. TcpView

TCPView allows you to view detailed TCP and UDP connection information in a user friendly format.

http://technet.microsoft.com/en-gb/sysinternals/bb897437

7. Microsoft Baseline Security Analyzer

The MBSA is a tool that can be used to detect missing security updates and typical security misconfigurations.

http://technet.microsoft.com/en-gb/security/cc184923

8. The Dude

The Dude from MicroTik can automatically scan all devices within a given subnet and then draw and layout a map of your network.

http://www.mikrotik.com/thedude

9. WireShark

WireShark is an interactive network protocol analyser and capture utility. It provides for in-depth inspection of hundreds of protocols and runs on multiple platforms.

http://www.wireshark.org/download.html

10. Look@LAN

Look@LAN allows you to quickly scan your network looking for active nodes. It provides monitoring, reporting, logging and OS detection features.

http://download.cnet.com/Look-LAN-Network-Monitor/3000-2085_4-10145550.html