I follow Errata Security blog for quite sometime. Living in defensive security, you will still have to see what people with offensive security mindset can come out with. I just came across this post from Errata Security and it's about base 16 - Hexadecimal magic and the role of it in computer security. Personally I like this post a lot(not because it has the same name as our HeX system) but one of the reason why I give HeX system its name is because of its evil spell(curse) and the hex number where packet monkeys need to deal with. More details can be found here. On the other hand, I used to mention this in my training class - it's important to master hexadecimal when comes to dissecting protocol header(mind you, more importantly the application layer protocol).
I think hex is double edge sword, it plays important role for both offensive and defensive security, the blog post from Errata Security demonstrates the use of hex number with short but incredibly clear explanation and I hope you enjoy reading their post too.
By the way, me and spoonfork will conduct the network security training for HITB again. I hope we can deliver new analysis mechanism for network based forensics and again we wish to see you in HITB Dubai in coming April 2008!!!!!