I keep notes in Vim+Dropbox on my laptop and Byword+Dropbox on my phone for easy syncing and simple, distraction-free editing. A webapp would be a great alternative if it's also usable from a phone. A single interface for everything, always kept up to date, with no distractions. If it could export to a local file for backups (or running notes through Markdown, if they become coherent enough), even better.

Congrats so far: it looks beautiful. And I have a few writer friends who would probably find something like this useful, especially the collaborative editing parts.