While I am waiting for word on a book out at publishers, I've done what most everyone advises - start another one.
I've started it. Barely.
I have about six chapters outlined, more or less, though when I write I find that I tend to add in different details or even ignore the outline as I go along.
Never gone is the specter of that "other" book, languishing on some slush pile or maybe sitting, forlorn, on some editor's desk. So I hope.
It's hard to forget something you've worked so hard on. Hard to get over it and go on to something else that easily, though I am trying.
So, what do you do when you are between books? Besides clean the fridge, eat or???