NethServer - NethServer is an operating system for Linux enthusiasts, designed for small offices and medium...
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.
ClearOS - A very good alternative for Windows Server, for free
Cisco Data Center Network Manager - Cisco Data Center Network Manager offers network management system (NMS) support for traditional or multiple-tenant LAN and SAN fabrics.
OpenMediaVault - OpenMediaVault is the next generation network attached storage (NAS) solution based on Debian Linux.
DCImanager - DCImanager is a platform for managing physical equipment. Connect any physical equipment to a single platform. Use the platform to manage your servers, switches, PDU as well as physical and virtual networks.