openDCIM is a Web-based data center inventory application which allows you to manage capacity and track assets throughout multiple data centers. There are some graphical elements to the system, but overall, the system is designed for keyboard-friendly (rather than click-happy) use. It is written in PHP and utilizes a MySQL backend for ease of deployment on nearly any LAMP-based build.
RackMap is a Web-based datacenter management tool. It was designed to help organisations catalog and manage datacenter assets such as racks, servers, routers, and switches. It allows you to catalog hardware location and cabling information, export data in various formats including PDF, generate bulk configuration scripts, and remotely control some devices.
Sequencer is an engine used by system administrators for the computation and execution of sequences of actions over hardware or software. It can ping various devices in parallel, power on your whole cluster, or generate an Emergency PowerOff (EPO) script for your data center or cluster. It takes into account various dependencies (power off nodes before switches, clients before server), deals with failures kindly, and is very efficient (>4000 nodes in less than 10 minutes).
Outlets is an AJAX-enabled centralized power distribution unit (PDU) manager. It has has been tested on APC and Tripplite units with SNMP functionality, but can work with other units given proper configuration. To change the name of an outlet, simply click its name and enter the new value. Press Enter to confirm or Esc to cancel. Outlets can be switched on or off by clicking the status and selecting the desired status from the drop down, then clicking OK. Changes are written via SNMP, thus each PDU must have an accessible SNMP write community. Outlets can use a standard LAMP setup, though it does not require or use MySQL. In addition, it requires the php5-snmp module. All PDUs must support SNMP v1 and be set up to allow the IP of the machine Outlets is hosted on to access SNMP. Some Tripplite units exhibit a behavior where they do not properly confirm SNMP writes and stop responding to requests for about 60 seconds after SNMP writes. They can still be managed (it's just a bit wonky), but the APC units work flawlessly.
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.
Symbolic is an enterprise platform designed to build, configure, and manage your huge and globally distributed data centers. It features cloud computing, Web manager virtual environments (Xen, KVM, and libvirt), clustering support, custom operations and scripts support, and user and role definitions.
MachDB is machine database to catalog of the changing state of your hosts. It consists of a database, an aggregator, an XML spec, and some example information gathering scripts. Along with a Web UI, these form the basis of a system that will allow you to catalog the current and historical state of the hosts in your infrastructure. It has been designed with scale in mind, and the goal is to support 10k hosts. It is being actively developed and is used in production at a few organizations.