I keep a notebook with me all the time to jot down ideas/thoughts for projects. Not my journal... just a "one day, when I get time, I will do this" sort of thing. When I fill a notebook, I go through it and record good ideas and get rid of dumb ones.

On November 19, 2008, I wrote:
humanist perspectives on divorce?
4 perspectives on the divorce for an audio documentary a la NPR
David. Crys. Derek. Colleen. Mom/Dad? 
Using journals/letters/etc.

I'm so glad that came to me. A year and a half later, my life is so much better for having that idea.