Here are some favorite monster type books that we own and enjoyed reading.
"Go Away Big Green Monster!" is a fun book. Making Learning Fun has great activities that go along with this book.
"One Hungry Monster" is a great counting book. A few years ago I made some different activities myself to use with my boys. I don't have them available, but I copied the monsters from the book and used them as I wanted. You can find out more about it in my 2010 post here.
Another book that is fun to read when talking about monsters is "Where The Wild Things Are". Making Learning Fun has great activity ideas to go with this book as well.
There are some really fun printable packs to go with monsters. 3 Dinosaurs has a huge pack with lots of great activities to go with monsters. I like her packs because she has easier stuff for tots and harder things for kids around kindergarten age.Little Monkey Printables has a Not So Scary Monster pack filled with great activities as well.
If you are looking for some math activities check out this blog post that has links to 25 math ideas.
Some of our favorite monster movies are "Monsters Inc" and "Monsters University". Check out Monster Universities home page for fun ideas.last year. He was more involved with the process this year aside from just gluing on the pieces I had cut out. It is fun to watch kids grow and learn. Of course, he had to demonstrate his monster face.