I already mentioned TreeSheets. The more time I spend with it, the more fascinating I find its idea. Here is an example what I like about it.  It was created with, you guess, yes, TreeSheets.

What I like about TreeSheets The idea Hierarchical Structured Compact presentation Intiutive GUI Easy to insert new cells Tricky ways to manipulate hierarchy My favorite: transposition left right <=> left right Formula handling More intuitive TreeSheets price qty total 2.5 3 1.5 * 4 2 6 10 6 9 sum 25 vs Other spreadsheets price qty total 2.5 4 10 3 2 6 1.5 6 9 Grandtotal: 25 Not documented yet