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.
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.
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.