RackTables - Racktables is a nifty and robust solution for datacenter and server room asset management.
AssetTiger - AssetTiger is a free community service and cloud-based asset management tool.
Opendcim - a free, web based Data Center Infrastructure Management application.
Wasp AssetCloud - Wasp is the asset tracking solution provider that offers all the necessary software, hardware, and asset tags you need to implement an asset management system.
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.
Reftab - Free asset management software with check in check out. Track assets with custom asset tags and mobile apps. Supports handheld scanners for quick item check out.