SolarWinds

Free
Enables you to scan Active Directory and optionally remove computers
Free
Track the performance of VoIP calls
Free
Affordable, web-based helpdesk software for ticketing & asset management
Free
SolarWinds Engineer’s Toolset contains over 50 network tools
Free
Export information from remote Windows 7/2008/Vista/2003/XP/2000/NT machines
Free
SolarWinds NetFlow Realtime - Quickly & Easily Identify Network Bandwidth Hogs
Free
It enables you to keep an eye on your entire VMware virtual infrastructure
Free
The program lets you analyze Wireshark packet capture files