Journaley is an open-source journal keeping software for Windows, which is compatible with the Day One app for Mac. I have been using Day One for almost three years. It works well, and I like it. I have used Journaley for less than a day, but it seems to work as advertised. I have set it up to sync with DropBox.
I believe it will be just as useful to people who don't use Day One on the Mac. In fact, it may be more useful, as it essentially reproduces the capabilities of Day One. It may be called "Day One for Windows."
I learned of the application from David Bosman