> This raises a related point that I've been wanting to make: it's just
> astounding to me that the best shell books are not available and/or pretty
> much out of date. For example: the most recent comprehensive book on North
> American shells is 25 years old!
And it took me months to find a copy
> available. Some say there's not enough demand--and I don't believe it. The
> first copy I saw available was at alibris.com, going for $480! Compendium
> of Seashells in getting hard to find (but I did find that one).
American Seashells is a vast and highly-researched work, and making a
replacement for it which improves sufficiently on the original to make a
difference will be a long, hard job. It's not just a question of sitting
down with the old one and a typewriter - I doubt whether there are more
than three people on the entire planet who could produce a worthy successor
to American Seashells within a realistic budget and timeframe. Factor in
the costs of production, which in real terms have increased since the
second edition, and the higher expectations of a better-educated market
(broadly speaking), and it's a wonder anyone is even contemplating doing a
new edition. The original was Tucker's monument, but he bent the rules to
breaking point in order to get it done.
The Compendium has just been reprinted, and Odyssey are selling it as
usual, so it shouldn't be hard to find.

> So, most of us are able to choose between basic non-comprehensive books
> such as the nature guides or specialized articles and books. The
> intermediate has been neglected.
No it hasn't; Gary Rosenberg's Encyclopaedia is a fine guide to the basic
distinctions between the various families, with splendid pictures. Cheap,
too. If you want to go a little further, Mollusca : the Southern Synthesis
is the next step - a brilliant, well-produced work which covers the various
families in great detail with good, clear figures. The best general work
there is right now, and likely to be so for a few years yet.

> I think there's a great opportunity for some enterprising enthusiast to put
> together a good book (books) or to devise a website that could serve as a
> universal identifier and that could be amended and updated with expert
> assistance.
As long as that enthusiast does something else for a living; but then, of
course, they won't have enough time to do a proper job of the book. See the
problem?