One way to demonstrate the flexibility of multi-version documents is to display the same information in several ways. Charles-harpur.org and Ecdosis now boast a table view, which displays all the versions of a work in stacked form, so an editor can quickly scan through a text to see what is a variant of what, no matter how complex the variation.
My XML-based rivals are still struggling to produce such views, but I doubt they will succeed. Their problem is that they record internal variants (deletions, additions, substitutions) inline as part of the text, and to produce a table view you have to tease apart these changes into separate layers, which is almost impossible due to markup variability. So this display, although it doesn't look all that earth-shattering, is actually unique. Also it is what textual editors have long been bugging me for.
Table view of part of The Creek of the Four Graves
To try with different poems, select a poem from the Browse menu, then click on the "table view" tab. Some poems are not uploaded yet and may not work, but most are OK. Some minor features: the table of sigla on the left is anchored. Mousing over the sigla shows their full name in case they are partly obscured. The spacing could be improved, but it is basically all there.