I carry around this tiny little pink notebook in my bag everywhere I go. Sure it has the odd phone number or book title in it but it's purpose is to catch random thoughts and ideas that I have during the day when I'm away from my computer. Sometimes I focus and think what could make ________scene stronger? Or how can I raise the stakes for so-and-so? Other times I'm talking about something and think: that was funny, clever, maniacal. . .and it should be in a book someday. Out comes the pink notebook and I jot it down.
I haven't used every line or plot idea yet and that's the best part. Sometimes when I'm feeling stuck I pluck out the little book and flip through it, I may not use anything but it can get my mind turning and that's sometimes all it takes, other times it takes chocolate. But that's a whole other thing!