We've just started a sale of our backlist titles. 50% off everything that was published before 2007. Just go to our website, and check the publication date listed on the book's page. When you check out, enter the discount code "Winter". This sale is going on through the end of the year.
We've got some pretty interesting books in our backlist. Here are a few more general interest ones that people might be interested in:
Origami Design Secrets
The Cryptoclub: Using Mathematics to Make and Break Secret Codes
From Zero to Infinity: What Makes Numbers Interesting
Project Origami: Activities for Exploring Mathematics
The Mathemagician and Pied Puzzler: A Collection in Tribute to Martin Gardner (and several other similar books)
How Noble in Reason