GutenRecs currently has recommendations for ~30,000 of Project Gutenberg's 40,000 book library. If you have any suggestions for the page, let me know.
A short writeup for the project, including technologies used, can be found here. You can also check out the project on GitHub.
Enter the book or author last name you'd like recommendations for, and we'll find you some similar books.
A few suggestions:
A Kindergarten Story Book by Jane L. Hoxie
The Merry Adventures of Robin Hood by Howard Pyle
Bible Stories and Religious Classics by Philip P. Wells
A General History and Collection of Voyages and Travels — Volume 09 by Robert Kerr
Great Expectations by Charles Dickens