I have written before about Google Books. (See http://blog.eogn.com/eastmans_online_genealogy/2006/10/full_text_genea.html.) This is a great online resource for genealogists. Thousands of old genealogy and local history books are available to you free of charge. You can download and save them on your hard drive, then re-use them time and again as you wish.
Some readers have found problems with the online books, however.
The books are scanned using a robotic book scanner. Books are placed into the machine by a human operator and scanned at a rate of 1,000 pages per hour. Sadly, it appears that no one checks the pages. Many pages are skipped and not scanned as the robotic page turner apparently allows some pages to "stick together." Other pages are simply unreadable.
Even worse, Google does not provide any mechanism for readers to report errors or missing pages; or to obtain the missing words or pages.
Google Books is a great service but still new and with a few growing pains. Let's hope it improves as Google gains more experience.