I agree with Christine, it’s notes in the margin that keep me going. I use a PDA.
At the end of each session, I save the work to my PDA, and throughout the day (and sometimes the night), I jot down quick notes to myself. Sometimes, even just highlighting a section is enough. One thing to remember though, is to make sure you remember that great idea. If I had a dollar for every time I have sat looking at a word or phrase that made perfect sense at three in the morning, but means nothing now, I wouldn’t need to type, I could have one of my staff do it for me.
After the fifth or sixth time that happened, I started recording voice notes instead of writing them. I would say what triggered the idea, what it was, and maybe a line of text. Then I could go back to sleep knowing I had it down in a way I was going to remember. And it works…IF you remember to hit the record button. After all, no system is perfect.