Earlier in the year, I attended and event where Author Chris Grabenstein brought up a very interesting point regarding book titles. When coming up with a title for a book, it's obviously important to have one that it's relevant in some nature to your subject matter. However, when you have a series, your goal should be not only that, but for the titles of your books to also have some relevance to one another as well. Sounds obvious enough, right? Here are a few examples off the top of my head: His own series that boasts titles such as Tilt a Whirl, Mad Mouse, Whack a Mole, Mind Scrambler, etc. Another example would be Uglies, Pretties, Specials, Extras, by Scott Westerfeld.
Here lies my pickle: When I started writing, I did it with 3 separate ideas, for 3 stand alone books, all with nice titles in mind already. Well as my characters and stories have developed, I've plotted to connect all 3 stories in what I think is a very interesting way. But those darn titles I had in mind? Don't have a darn connection in the least bit with one another! So I'm back to kicking around ideas in my spare time. Good thing nothing is final until you're dead...and I think even then there is room for negotiation.
Just something to think about.