I would suggest checking against the corpus before
saying "x should be
enough for anyone". There are also occasional but valid uses for
non-standard sizes.
Perhaps generate the standard thumbnail sizes at upload time and then generate
and cache tumbnails of non-standard times until they haven't been accessed for a
few days.
Doesn't take up much space, like just deleting all the thumbnails that are
generated, and it saves time down the road as the most common thumbnails are
already generated.
I wouldn't rely too much on the Squids. They do an excellent job, but thinking
of those of us who use Mediawiki outside the foundation, I would much rather see
an intelligent thumbnail generating and caching scheme that doesn't rely on
Squid being present.
Thank you,
Derric Atzrott