There's an interesting article at the online mag Fine Books and Collections about collecting Abecedariums. I can't figure out how to snag the image so you'll have to go look.
You can look at the sample issue for free - to find this article just click contents up at the top. This number also includes a profile of Robert Sabuda, who they dub "the Prince of Pop-ups" and a very interesting Paul Collins piece all about a reprint edition of David Copperfield which includes all the ads which appeared in the original serial printing. Fascinating stuff.