One of the most common pieces of advice I've read is to take every possible moment to write. The whole point of NaNoWriMo is not just to drive aspiring authors insane, but to foster the habits of daily writing.
What tools can help an author on the go? Software like Scrivener is great if you're sitting down at a desk, but it's not as helpful when you're on the go.
My challenges in time management mean that I need to be able to write anywhere, at a moments notice. Lugging around a laptop just isn't going to cut it. Even carting around an iPad isn't going to give me the flexibility I need.
I've already started writing my novel on the iPhone. It's a compact device I always have with me, and it's possible to type one-handed. I'm impressed with the autocorrect behavior, even when typing one-handed.
While typing speed may not be as fast as with a full-sized keyboard, the main point is that you can write when you otherwise wouldn't be able to. You can fill in those otherwise dead spaces, and actually write.
The recent advances in cloud computing allow the work to be saved online, which both provides backups as well as the ability to resume writing on a different device when the opportunity arises. For example, this post was composed on the iPhone to this point, where I switched to writing it on the iPad with an attached bluetooth keyboard. Before published my post, I did a final edit on the desktop in a browser.
If the primary block to writing is finding the time, consider using a mobile platform. A common saying in writing is "butt in chair, hands on keyboard", but that doesn't really serve the mobile writer very well. To fill in those smaller blocks of time throughout the day, I've found that I need a solution that doesn't involve sitting in a particular spot.
As a tool, I'm using the Elements text editor on iOS, by Second Gear software, which has Dropbox support. It has a folder structure, which allows me to group files together, and separate the work by chapter, or as supplemental notes. Also important is the easy info button which provides the important word counts. Because it's plain text being stored in Dropbox, it's easy to do any later edits on the desktop.