Aibase is also a Windows program which can calculate with SI-unit expressions:
http://www.aibase-cs.com/quantities.html
It's not a true spreadsheet program, because calculations are based on script, and version 3 has no functions to create large tables. It might be of interest though if not an...
Morton, the term "mindmap" describing the diagram is tending to be a bit provocative, that's all :). Otherwise, I can see that it can be useful as organizer and brainstormer.
Best regards
I think, mindmappers (= spider diagrams) are mostly too restrictive for engineers. What they call mindmap is a simple hierarchy (1-to-n relationship), but spiderlike arranged. We had a young colleague with a mindmapper on his notebook, but he removed it soon. The most used "PIM" software in our...