One very common request I've seen is to be able to create network diagrams like those produced by Visio. In response I've created a set of shapes that are styled in a similar way to Microsoft's (http://www.vrt.com.au/downloads/vrt-network-equipment) and these are also hosted at extensions.libreoffice.org under a CC license.

While LibreOffice Draw doesn't have comprehensive support for isometric diagrams or grids, some of the shape and text already have faux-perspective and it is possible (using a 1.723:1 grid as per this http://www.draw-shapes.de/?p=79) to create quite reasonable diagrams that use isometric shapes.

If LibreOffice supported connectors that snapped along 30 degree lines (http://www.visguy.com/2007/10/29/oblique-connectors-for-your-3d-diagrams/), in combination with the shapes and grid above, I think LibO Draw would provide a compelling alternative to Visio for people wanting to create network diagrams.

If having in-built shapes to match the connectors were to help get a case for building the connectors across the line, then I may be able to get my company to contribute them to TDF for inclusion in LibO (not sure whether that is even desirable, or if continued existence as an extension is preferred).