Quickly create diagrams of all your racks, showing location of all servers within rack, and cabling if required.
Create connection diagrams showing the back of servers with the correct connections going to the correct ports.
Use to guide engineers, to build racks and cable them properly, or when sedning engineers to remote datacenters so the correct cable gets tested etc.

LEO is an outliner, but by implementing a visually compelling directed acyclic graph (DAG) instead of a strict tree, it allows one to present multiple aspects of structure. Some "branches" of the graph can generate source code, others configuration files, others comprise documentation which includes analogs of "hard links" to portions of the code or configuration; various aspects of the subject can be pulled out and collected into coherent subsets independent of each other's structure.

Example: sendmail.mc generated by one tree, other trees within the graph contain source for the various .m4 files, while a documentation tree contains text but also nodes from the various files making the specific implementation immediately available for modification along with the documentation.