I can’t believe I only just heard about Notation. I’ve been using it for a few days now and it’s exactly what I’ve wanted on Windows. It’s literally just a Notational Velocity clone. It’s simple and effective.
Previously I’d been using Notepad, pinning frequently accessed text documents to the icon for easy access. What a mess. This is much better.
ResophNotes is a similar clone, but I haven’t tried it.