The Gutenberg project is host to many free e-books (in different formats) including some interesting Needlework books. These are mainly older books in English that are in the public domain. If you search for 'embroidery' or 'needlework' you will find a few interesting books like this book about Jacobean Embroidery and the famous Encyclopedia of Needlewerk by Therese Dillmont.
The Antique pattern Library is another interesting resource for all kinds of non-copy righted publications for different types of Needlework (as well as other crafts).
More and more museums are putting their collections online too, some of them are very extensive like the Metropolitan (6173 hits when I searched for Embroidery, 10494 for Needlework!). The collection of the Victoria and Albert Museum is definitely worth browsing too.
Perhaps somewhat more difficult to search for most is the Dutch Rijksmuseum online collection. However I found some lovely examples using the dutch word for embroidery (which is 'borduurwerk') like the late 19th century silk shoes you see pictured above.
this allegorical embroidery from ca. 1800, made by Louise van Ommeren? Check out the furry stitching on the man's cloak and the shading on the lady's robe!
What are you stitching? Please share in the &Stitches Flickr group. We'd love to see it!