Shaun Usher posted a wonderful letter, from Robert Heinlein, on Letters of Note. Heinlein sent the letter to Theodore Sturgeon.
"I went into a horrible dry spell one time. It was a desperate dry spell and an awful lot depended on me getting writing again. Finally, I wrote to Bob Heinlein. I told him my troubles; that I couldn't write—perhaps it was that I had no ideas in my head that would strike a story. By return airmail—I don't know how he did it—I got back 26 story ideas. Some of them ran for a page and a half; one or two of them were a line or two. I mean, there were story ideas that some writers would give their left ear for. Some of them were merely suggestions; just little hints, things that will spark a writer like, 'Ghost of a little cat patting around eternity looking for a familiar lap to sit in.'
The entire letter is posted. It's great reading. Heinlein is my favorite author and this letter demonstrates why. He was very creative and I would have loved to have seen the full stories that he could have written from these ideas.