I'm curious to learn how designers throughout history have dealt with this problem Joni mentions — typesetting a small amount of content, or content in a specific (and therefore limiting) format, given a spacious canvas.
Off the top of my head, some options are:
* Size to fit (success depends on reading distance)
* Flow to multiple columns (CSS can't reliably do this yet)
* Establish specific boundaries using edges or borders
* Establish periphery using subtle color shifts or illustration
* Position content tastefully, risking feeling of emptiness
Part of me wants to believe that designers throughout history, because of the finite nature of physical materials and the ability to dictate paper size, never had the problem of too much space.