It seems that Google (NASDAQ:GOOG) is never lacking for innovative surprises. A recent Wall Street Journal report revealed that the search behemoth is considering a rental service for online books.

Apparently, the company pitched a plan to an unnamed publisher to offer short-term access (about a week) to book content for roughly 10% of the purchase price. Users could only read the book online -- they wouldn't be able to print or download the content. However, the publisher reportedly refused, saying the price was too low.

It's just the latest round in the recent contentious efforts by online giants such as Motley Fool Stock Advisor pick Amazon.com (NASDAQ:AMZN), Microsoft (NASDAQ:MSFT), Yahoo! (NASDAQ:YHOO), and Google to create a virtual library. The technology isn't the problem; instead, these companies are becoming tangled in thorny issues of copyright and content ownership, as publishers and authors alternately condemn or support the idea of making their books' full text available online.

Yahoo!'s approach is to partner with leading universities, scanning only books that have lost their copyright protection and entered the public domain. For copyrighted works from living writers, Yahoo! intends to get an author's permission to scan his or her books; Microsoft has taken a similar tack in its own efforts.

Amazon.com plans to offer two programs. Amazon Pages will allow readers to buy particular pages or chapters of a given work. (How many times do you buy a book just to get a certain part, anyway?) Amazon Upgrade gives customers who buy a physical book immediate access to its online version for a small additional fee -- perhaps a couple bucks more.

Google's also taking a two-pronged approach. Under the less controversial Google Print Publisher Program, the company gets permission to scan books for its search engine. Publishers can restrict users' ability to see anything more than small parts of a book's content.

The other program, the Google Print Library Project, is creating a firestorm. Google is scanning thousands of copyrighted texts, intending to make them freely searchable online. The move has led two major organizations - the Authors Guild and Association of American Publishers - to file lawsuits. There are currently no signs that the publishing industry will drop its fight against the Google Print Library Project, and the case may prove to be a landmark in Internet law.

"Publishers were burned in the late eighties and early nineties with promises of online eBooks and courses," said Alex Pereira, COO of Xplana, a company that provides technology to help publishers like Houghton-Mifflin, Thomson Media, and Wiley create digital versions of their books. "Online publishing is a new paradigm for the traditional publisher. It will take time for them to get their content into this new medium."

Digital books could become an important additional source of online ad revenue for companies like Yahoo!, Microsoft, and Google. Still, investors ought to question how well these digital library projects, and other media-related ventures, fit into these companies' core goals. Searchable books online do seem like the next logical step in the migration of information to the Internet, but consumers have given online books the thumbs-down in the past; is there a market for them now? And if they're willing to branch out from search engines and software into virtual libraries, how far do these companies plan to extend their reach in the future?

Fool contributor Tom Taulli does not own shares mentioned in this article.