Actually I think we don't need a DB but just a table
somewhere on the site with the list of books available.
At least until we have so many books available that we
need a DB to list them.
Plus I think each book in the Book Reviews section lists
the ISBN, so you can probably get it from vroom.
If you really want an ISBN search I found there
a search thingie that retrieves the title for a given ISBN,
It found the Camel 3, but then the tool went down before I had
a chance to test it further :--( I'll keep you posted on
whether it also works for less common titles as soon as it comes back).
Update: the store seems to have a good collection,
they had the Camel 3, Web Client Programming with Perl,
the MySQL book by Paul Dubois and the XSLT book. They
just missed a Unicode book that's about the most arcane
book I own.