NethServer - NethServer is an operating system for Linux enthusiasts, designed for small offices and medium...
Cisco ACI - Application Centric Infrastructure (ACI) simplifies, optimizes, and accelerates the application deployment lifecycle in next-generation data centers and clouds.
ClearOS - A very good alternative for Windows Server, for free
NSX - Data Center Networking
Univention Corporate Server - Univention Corporate Server UCS with Active Directory functions and App Center is the cost-efficient and popular successor to Microsoft's server solutions.
ManageEngine OpManager - Monitors routers, switches, firewalls, load-balancers, wireless LAN controllers, servers, VMs, printers, storage devices, and everything that has an IP and is connected to the network.