A valuable area to target: Concurrency Optimization. Another: Low-Level Optimization and Memory Hierarchy. Books on these already exist, but Zed has the attention of a large swathe of the programming populace that could really use more awareness on these topics. That potential energy could be converted to book sales or sales of some sort.
EDIT: Translation - sure let's hang out. Seems worth a try. You can send email to this user name at yahoo dot com.
Either it's working so damn well nobody needs to tell me because they end up writing their next million dollar idea a week later, or it's really not working and people are just not bothering to tell me.
Thanks.
Two of my friends have commented that they really like the snarky humor. I think it's a part of what keeps them chugging through the designed-to-generate-errors-you-must-debug drudgery.
EDIT: Going back over the book, Exercise 0 caused one of my friends some confusion. The other sailed through it just fine. The confused one is a Windows user and hadn't seen the command line since Windows 3.1. The non-confused one has an Ubuntu netbook. Confusion was over what constituted commands to type in and what was the part you should see. The mode switch between the Python prompt and the CMD command line also took a few minutes of explaining.