No. Sadly as each app would have to support such a note there can't be a Windows app that does this. Such an app would have to co-ordinate such notes with each app. As the Windows OS does not have such a tag for the files, there is no such app.
Bob
I am looking for an application similar to OneNote. However I want to be able to post a note in the datafiles of other applications.
For example I would like to be able to post a note inside a read email message that says something like "phoned the sender to discuss problem and we decided to ..."
Or post a note in a spread sheet that said. "Don't for get to double check this entry with Fred."
The app would have indexing and search capabillity and allow the note to be linked to a todolist or calendar.
Has anybody seen anything like that?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic