The majority of books are rarely worth the read and I can't think of a ColdFusion title I'ce pored through that I'd be willing to recommend.
With so much free information available online, have you considered some of those resources ?
Macromedia have a ton of ColdFusion articles, samples, tutorials and so on:
WebMonkey have some good intro articles:
A very simple intro can be found here:
SitePoint have a nice intro:
The superb Planet Source Code click here cover all the major languages and have tutorials and sample applications for you to play with.
The Free Programming Resources site click here has details on various ColdFusion articles, among other things...
Perhaps someone else will suggest a book, but as I've said, I've yet to read through a ColdFusion tome that I was particularly impressed with.