If you're looking for a way to take and organize notes, hardcore Linux users will tell you that Vim or Emacs is the only way to go. While they're both excellent solutions, neither are for the faint of heart. There are plenty of note management options out there -- Tomboy and BasKet, for instance -- but why not ratchet things up a notch and create a digital journal instead.
Zim is a really WYSIWYG text editor that's more than just a note-taker. In fact, it bills itself as a wiki for your desktop. "A "desktop wiki" means that we try to capture the idea of a wiki, not as a webpage but as a collection of files on your local file system that can be edited with a GUI application. The main focus is a kind of personal wiki that serves for all kind of notes: todo-lists, addresses, brainstorm ideas etc. "
Written in Gtk2-Perl, Zim works on both Linux and Windows. It saves data "transparently" as plain text files so they can be opened with any file manager or editor. You can even put your content in a revision control system, compile it into a Web page using a Makefile, or export notes to HTML.
There are a handful of plugins available that extend Zim's funtionality even further. A spell checker, equation editor, and a todo list dialog and among the options available now, and future plans include things like tags, albums, and a mindmap widget.
A good information management apps is crucial to avoiding information overload. Plain text editors get the job done, but when you need something more robust, Zim is definitely worth a look.