Earlier today I spent a bit of time rediscovering how you can frequently take XML data and make it palatable in a Web browser with no more than a couple dozen lines of CSS. Not the most accessible unfortunately, but for visual rendering ::before/::after and the content property are pretty powerful. And of course if you need more power and better accessibility there's always XSLT. And if you use fragment references in your <?xml-stylesheet?> declaration you can manage this with no external resource dependencies.

It's just really cool to me to have a file that is at the same time both valid machine-readable data and decent to look at.