Recently Joshua Hutchinson has been uploading eBook pages images (as PNG format) to the PG website.
For example;
The page images of Spacehounds of IPC, by Edward Elmer Smith are in the folder;
http://www.gutenberg.org/dirs/2/0/8/5/20857/20857-page-images/
The “system” used to number page images is as follows;
Covers (front and back) and the illustrated inside covers and marked = cXXX.png
Front matter (title pages, contents, introduction, preface, etc) = fXXX.png
Main body = pXXX.png
End matter (index, appendix, etc) [only if number starts over] = zXXX.png
Images inserted without a page number are given the closest page number with -insert extension (ie, p100-insert.png)
Images scanned at a higher res from the rest of its page in a separate file get -image extension (ie, p100-image.png)
Currently, Josh is only grabbing images from the Distributed Proofreaders archives (for images we have permission to reuse like this). If anyone has images from other locations they want to add please contact Josh at jhutch2000@gmail.com.