More or less copyright free, and Dover seems to want you to use it for whatever makes sense to you. And the books are relatively inexpensive, on good paper. And they've been on sale here recently (early fall 2008)
That said, I'm not sure there's a whole lot in the way of images I can use for quilting designs here.
Which is OK too, because they are a lot of fun to browse.
Average Rating:

Edition: illustrated edition
ISBN: 0486404714
Number Of Pages: 64
Languages:
Original Language: English
Unknown: English
Published: English
Product Description:
Outstanding collection of over 400 designs and illustrations, selected from authentic sources of medieval and Gothic ornamentation, includes woodcuts of human figures and walled cities, images of fanciful beasts and creatures of the sea and air, drawings of turreted castles, knights in armor, and much more. Perfect for adding a rich period flavor to catalogs, brochures, magazine articles and other print projects, this copyright-free material will also serve as a practical sourcebook for a host of art and craft projects.
Features:
- ISBN13: 9780486404714
- Condition: NEW
- Notes: Brand New from Publisher. No Remainder Mark.
Available at Amazon
List Price: USD 6.95
Lowest Used Price: USD 4.12
Lowest New Price: USD 4.08
Customer Reviews

Great reference, small variety
Unless you happen to still paste up keyline boards and need clip art to literally "clip out", the Dover Ready-to-Use books offer less images for the price. They're printed on slick, hard paper with nothing on the back of the page. I discovered that half of the same images were available in my other Dover reference books of similar themes. The picture variety spans a broad spectrum of the Middle Ages and Renaissance with lots of etchings and the occasional celtic knot. It's a good reference, just limited.

Clip Art
Of the Dover Books, this is one of the most interesting. The only caveat is they don't offer it with a CD like so many of their books. Highly recommend for hilighting projects. It adds alot of detail to manuscripts, music, etcetera.