Another thing I use frequently is sticky notes. I jot little notes and reminders to myself and stick them with my calendar or task list or on my laptop where I'll see them when I sit down to work.
As a result, my book and task lists are a little sticky note crazy, especially now that we're at the end of the month. Reminders about ending projects, updating files, and generally keeping myself organized as I get ready for October. All in sticky note form.
The reason I like sticky notes added to my calendar and task list is because they can be added, removed, and moved around without crossing things out or using white-out. Much easier for quick notes. And they add a bit of color to my pages, which is always nice.
Do you use sticky notes to help keep you organized?