A simple note making application with human-readable/writable storage

Question

I'm looking for a simple application for making notes. My requirements:

1. Simple storage format. I mean it. I want to be able to browse and edit my notes using a text editor (like notepad or Emacs), sync via Dropbox (or any other cloud), maybe even put it in a version control system like Git. This is my primary and most important requirement. And it must be relatively close to plain-text, so no XML.
2. Apart from taking notes, I want to be able to tag them and search by tags, creation date, modification date etc. (that's why I want something better than a text editor).
3. Windows and Linux must be supported.
4. Open source solution is preferable.

Not important:

1. Fancy formatting or storage of non-text data (pictures, videos, etc.).
2. Built-in synchronization.
3. Support for iOS/Android.

AFAIK, no popular note-making application focuses on my most important point. I want to be sure that no matter what developers of the application do, I have access to my notes. I've been using Opera browser for taking notes for several years. I had a lot of trouble exporting them when Opera decided to drop the note feature from them browser.

Answer 1

Rednotebook is an excellent note taking and journalling program.

1. Simple storage - The data is stored in plain text files, no database is needed and archiving is done as zip files. Text is stored as markdown in .txt files.
2. Date based
3. Windows/Linux & OS-X available
4. Free & Open Source - Yes rednotebook is written in python

You can include fancy formatting, pictures, etc., but formatting is markdown and other items are simply referenced from your text not a part of it.