Journals are great for jotting down random thoughts but here are some other ways in which they can be valuable:
- A journal on the history of your house. It can contain details on repairs and warranties as well as information on various repair workers in your neighborhood. Six years from now, you may not easily recall who painted the eaves of your house.
- A journal on the presents you've given to others. Was it your uncle or your niece who got the book about Paris?
- A journal on your trips, where you stayed, restaurants you visited, etc. This may be combined with a travel diary.
- A medical journal with information on doctor's visits, inoculations, etc. I've found this to be very helpful.