RackTables is a tool to manage tens of racks, hundreds of servers, and thousands of MAC and IP addresses. It will work with a single rack as well. It features a real-life rackspace model, typed rack objects with flexible attribute sets, a tagging system, IP address management ready for NAT, virtual routers and load balancers, accurate network connection handling, a universal search function, a multi-user access model, and an extensible dictionary.
ITDB is a Web-based tool used to store information about assets found in office environments, with a focus on IT assets, but not limited to such. It will help you keep track of hardware, software, relationships between assets, invoices, locations, contracts, people, and rack layouts. It can also print labels for all assets.