I recently discoverd a site that scans illustrations from old books and makes them available to the public for no charge. Old Book Art is owned by an antique book dealer. The purpose of this site is simply to share public domain resources. Zephyrus Books comes across a lot of antiquarian books with wonderful old illustrations in the public domain. Many of these are not available for public sharing anywhere on the internet, at least not in an easily accessible or larger scale format, so this site was started as a free resource for anyone looking for out of copyright images.
Are there restrictions on how these images may be used? No, commercial or personal use for any purpose is perfectly fine. This site posts only public domain content and as such cannot put any restrictions on it.
I love illustrations from antique children's books. This picture of the girl looking at the moon is an example of an illustration from this site. WARNING: Do not go to this site unless you have plenty of time to browse...you won't want to leave any time soon.