I don’t know of any Jewish teachings directly enjoining us to financially support enterprises, such as WikiMedia Foundation or favorite, oft-used sites provided by individuals or organizations. But I do know that various kinds of “borrowing” are regulated:
For example, Shulchan Aruch (Orach Chayim 14:4) permits using another person’s tallit or tefillin. But some teach that this is only allowed in order to fulfill a mitzvah and only on occasion.
Fair use in U.S. law and in Judaism has become more complicated as electronic sharing has become more accessible. It is clear, of course, that it is unethical and illegal — both Jewishly and in U.S. law — to use a copyrighted work without permission (except as permitting in reviews and discussion) or to use someone else’s writing, even if copyright free, without attribution.
The case of using on-line resources, like Google Books, is perhaps more complex. I use Google Books sometimes to search — for my own purposes — items I already own, because it’s faster or I’m away from home or, sadly, I can’t find my copy. This seems obviously “fair use” in all senses of the word.
In addition, A Song Every Day often links to Google Books for volumes I own, as well as those I don’t own, on the theory that this gives readers a chance to see the quoted material in context (willingly shared by publishers) and to examine a book, as if on a store shelf or, perhaps, lent by a friend. I don’t know of any U.S. or Jewish law prohibiting this.
However, if any of us is using Google Books or a similar site to avoid purchasing a book we would buy if not for Google Books — and thus denying the author, the publisher and a book merchant a sale — my guess is that is prohibited the same way that lower-tech versions of interfering with someone’s livelihood are prohibited.
I don’t have handy sources for these prohibitions, but if you do — either to support or challenge my “guess” — please share them.
For many useful discussions of Jewish business ethics, visit the website of Professor Hershey Harry Friedman of Brooklyn College.
Also see articles by Dr. Meir Tamari, author of With All Your Possession: Jewish Ethics and Economic Life.