The gallery syntax is highly useful, but it assumes one monitor size and
resolution for everyone.
First, the generated HTML gallery-block should not have a fixed width, but
rather expand to fill the width of the browser. This would prevent the images
from squishing up against the left side of the window on high-resolution
displays. (Or, for that matter, displaying as a long, narrow strip down the
middle if the gallery itself is centered.)
Second, the thumbnail size used in the gallery should be configurable,
preferably through a user setting. (Allowing constructs like [gallery
thumbsize=200px] is asking for trouble.) Thus, a user on a 640x480 display could
use 100x100px thumbnails, while a user on a 1280x960 display (or someone who
just likes their thumbnails big) could use 200x200px. To prevent an overload of
thumbnails, the server could provide a few standard resolutions for the user to
pick from, say 50, 100, 150, 200, 300 and 400 pixels square.