The best way to keep track of all the crazy, smart, useful, funny, or lucritave ideas going through your head in a way that allows you to reflect and expand upon them. Your personal dumping ground for stuff stuck in your craw that continually distracts you from your task at hand.
Can be a great way to connect ideas into a great comprehensive plan and because of this, your idea journal should be kept separate from your general journal to allow you to focus on ideas alone. You never know what you may miss if you lump ideas in with other non-related stuff.
Jonasson Enigmatic Nirvana 