a word processor is ok (you can make a table of contents, add comments, notes, insert pics and text areas, design your own template, export in whatever format you see fit...).
openoffice is very good
if you do not export on a "webOS" type doc, you can still manage your doc with a portable app (you carry it on a USB, you use it anywhere w/o having to install):http://portableapps.com/
other than these, you can work online:
- gdocs has been mentioned --good, intuitive, reliable
- notebooks (I think you can still get gnotebook in your google account, although this lovely service is no longer further developped)
-or a CMS (blog mainly) which you can set on "private" if you just want something for yourself and like the "journaling" idea and the simple organization this kind of soft offers (archives by date, tags).blogger is free and has improved on usability since launch.
and, as for any data, never forget to save your tea data...