"The records consist of information describing works—including creator, title, publisher, date, language, and subject headings—as well as other descriptors usually invisible to end users, such as the equalization system used in a recording. "
I'm having a hard time thinking of what could be done with this data besides a library catalog.
I used to work in libraries for awhile and there's a pretty wide range of things this is useful for.
Lot's of interesting data analysis similar to what people are doing with google n-gram data for culturomics[0]. For example since you have publication year and subject heading you can look at the shift in popularity of certain subjects over time. I remember for fun I once plotted the life spans of various people by there area of research (art, math, sciences etc) it was interesting because there did seem to be some trends.
If you're doing any text classification research you now have a great way to label data if you just have title and author data. Or if you have texts with poor metadata you might be able to use this set to clean that up.
For libraries themselves I would love to see some machine learning approaches to cleaning up messy records, or just replace bad records with good one directly.
The big thing is that this is a very large set of curated bibliographic metadata from a reputable source. If you have any large project related to books (directly or indirectly) this could be a huge asset
You could merge this data with an online bookstore to get something that's like a library catalog in some ways but lets you buy the books.
If you're interested in "generic databases", like myself, books (and other creative works) are interesting because they are about various topics. Knowing what books have been written about what subjects is a bit like having preference data from millions of users, except there's more coherence, so you can do more with less physical data.
The first thing that comes to mind is that I should never have to type more than a couple of characters into a citation manager when adding a book.
Outside of the numerous uses for citations, reading lists, etc. I imagine that this is a very interesting dataset for researchers in publishing and library sciences. It is also a great resource for anyone developing library related software.
I'm having a hard time thinking of what could be done with this data besides a library catalog.