It was only a few years ago that online booksellers had only a couple of options for listing their books on Internet marketplaces. Enter Amazon.com, and suddenly there were some radical changes in the landscape as well as a huge market for online booksellers. Amazon has modified the way many things are bought and sold through the Internet, but their greatest influence has without a doubt been with respect to books, CD's, and other goods with standardized numbering systems, e.g., ISBN and barcode identifiers. When they began to allow third-party sellers to sell used items alongside the new ones Amazon was offering, many people, and certainly some other businesses, thought they were crazy, but Amazon.com maintained that they were customer-centric and intended to provide a marketplace where their customers could make their own decisions while being assured of a satisfactory experience.Recently, some very interesting events have taken place that warrant at least a cursory look. Google introduced Froogle quite some time ago, but recently introduced Google Base which I believe is intended to be the long-term replacement for Froogle. Google Base offers a venue for online booksellers to list their Amazon inventory for sale and potentially a means for sellers to circumvent the sales commissions charged by Amazon.com. While Google Base is still in its infancy, once Google has all the details worked out and has integrated into their service a means for secure customer payment and seller notification, Base will in all likelihood be a real headache for Amazon.com. I say this because Amazon.com is accustomed to market domination and Google is not very well known as settling for being number two at anything. I am sure Amazon.com will counter with other incentives and features to maintain their position and market presence, but Google will go for position number one in online bookselling if they really decide to get into the business. The developments are going to be very interesting to say the least.An even more recent development that lends credence to the value of the bookselling market was Microsoft's announcement that they will be launching an Internet book search feature which will target only books in the public domain and those that publishers ask to have included which are under copyright protection. Thus, Microsoft is now at about the same point where Google was a few years ago, but is not targeting all books like Google first declared they would be doing.So, why are Google and Microsoft so interested in books? The only logical explanation is that both see a way to derive substantial revenues from the sale of books. What I do not understand is why it took them so long to see this. Amazon.com is a multibillion dollar company with very respectable annual earnings, and surely Google and Microsoft were aware of Amazon.com's business theme before now. Amazon.com did not get as big as it is by giving their services away.