Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
RackTables - Racktables is a nifty and robust solution for datacenter and server room asset management.
GLPI - GLPI is the Information Resource-Manager with an additional Administration- Interface.
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.
Spiceworks Help Desk - Help desk software features that work for IT
Opendcim - a free, web based Data Center Infrastructure Management application.