If you haven’t tried using the Google Library feature yet, you should check it out. I have been amazed at just how large of a collection they are serving up. According to Wired, this doesn’ t yet include the disputed works. I’ve been able to find some very obscure engineering texts as well, but just typing in the name of the book and searching.
Examples
So far, this feature is not unlike the "Look Inside The Book" feature at Amazon. However, having the world’s texts in searchable format has the potential for enourmous change in research. Of course, it will take someone like Google to sort out all the information and actually find something relevant.