Microsoft has updated OneNote, the very popular “digital notebook” that they released for Macs back in March. OneNote became free with that release. Prior to that, when it was Windows-only on the desktop, it was not free.
Similar to Evernote, it allows you to add and edit notes across multiple platforms. LifeHacker had a very comprehensive comparison between Evernote and OneNote. I can see the appeal for OneNote, and I know a lot of genealogists who have been using it on Windows for quite some time.