I answered a post on the DNN Forum the other day relating to a question about how to go about structuring a custom build DotNetNuke® module. It's an area probably covered well in various DNN books, but I think it's a question that most experienced developers but first-time DNN module builders ask. Here's how I recommend you structure and build your custom DNN modules.
A little while ago, I posted a blog entry as a guest blogger on seablick.com. I'm putting a link in this blog to that entry, so that anyone searching for it here can find what they are looking for.