I don’t know how new this is, but it’s new to me. References to books within Wikipedia articles can contain ISBN links that, when clicked on, let you see what libraries have that book.

The default link takes you to a page with links to WorldCat and to individual library catalogs arranged geographically. But if you have a Wikipedia account, you can customize it so that the ISBN link searches for the book in Quest (or whatever OPAC you want to point it to.)

For an example of the default search, see Books on Charles Mingus in the Wikipedia entry on Mingus.