Useful little things. Sticky notes are handy things for all sorts of uses. Leaving a note for someone where they can't miss it. A bookmark that won't fall out. Adding an extra note to a page you've run out of space on. Attaching your password to your monitor so you won't forget it (actually, no, don't do that). Sticking a note somewhere unexpected for someone to find at a surprising time.
If you like to keep your journal looking beautiful, quickly scribble on a sticky note, then write it more neatly for real later. If there's something you're going to need to be reminded of for a few days, stick it on your daily page and move it, rather than rewriting every day. Stick one to the back of your phone, so you can scribble a quick note when you don't have your notebook handy.