Trotter wrote:
Microsoft have been assisting libraries with scanning of books that are now out of copyright at books.live.com.

I did a search for Tolkien and found that a copy of "A Middle English Vocabulary" has been scanned and is free to download as a PDF file, you can also search the book as it has been run through OCR software.

I don't own this book, so it is very nice to be able use it as a reference book.

You can download it here.