So, I took a long slow look at ten of the examples from Godmar's file.
Nothing I saw disabused me of my opinion: "No preview" pages on Google
Book Search are very weak tea.

Are they worthless? Not always. But they usually are. And,
unfortunately, you generally need to read the various references pages
carefully before you know you were wasting your time.

Some examples:

Risks in Chemical Units
(http://books.google.com/books?id=7ctpAAAACAAJ) has one glancing,
un-annotated reference in the footnotes of another, apparently
different book.

How Trouble Made the Monkey Eat Pepper
(http://books.google.com/books?id=wLnGAAAACAAJ) sports three
references from other books, two in snippet view and one with no view.
Two are bare-bones bibliographic mentions in an index of Canadian
children's books and an index of Canadian chidren's illustrators. The
third is another bare-bones mention in a book in Sinhalese.

> If the patron is sitting on a computer (which, given this discussion, they obviously are), the
> path of least resistance dictates that a journal article will be used before a book.

An excellent example. Let's imagine you were doing reference-desk work
and a student were to come up to you with a question about a topic.
You have two sources you can send them to—the book itself in all its
glory, and another source. The other source is the Croatian-language
MySpace page of someone whose boyfriend read a chapter of the book
once, five years ago. You're not sure if the blog mentions the book,
but it might.

That something provides the path of least resistance isn't an argument
for something. It depends on where the path goes.