I find myself writing as much as coding these days. Since most of my coding is split between Java (WebObjects) and Objective-C (for iPhone/iPad), I have a tendency to lag when it comes to operating system upgrades. Nothing causes more headaches than your dev environment's Java version getting rev'ed right in the middle of a big project.
So when I'm writing proposals, working on my next book, blogging, or just working on a cool D&D campaign idea, I find myself using my iPad more and more. Of course, a keyboard/case combo helps quite a bit, but nothing beats a nice screen (easy on the eyes), light weight, and long battery life.