Wikis are a great idea, whether it is for massive documentation repositories like Wikipedia or for organising notes and ideas on a smaller scale, they are easy to use, read and modify. the only drawback is that they generally need a web server to run, which makes them less useful for desktop use, and completely useless when you have no network connection.
Wiki on a Stick (in short WoaS) is a wiki that lives in one self-modifying XHTML file. It's perfect to be used at home or at office, on your laptop or USB pen drive. It can be used as a personal notepad, calendar, repository for software documentation and for many other purposes; it allows full customization and extension by your own scripts and plugins. It also offers AES encryption of pages.
A superb way of carrying important information around with you