What's in a name? Book titles...

While I was discussing book covers, erotic romance writer Celia Stuart posted about how books covers like book titles can't be copyrighted and that's why there are so many titles that are similar. So that got me thinking about the book titles. And being a little paranoid, last night I found myself researching my working titles on B&N and Amazon.com. Luckily most of them aren't taken. I admit I strive to come up with a title that's not exactly totally unique, but somehow pertains to the story. For me, the title has to somehow reflect something on the story - be that the theme, the mood, the setting, the characters, etc. Yet I've never considered the importance of the uniqueness of a title of a book, and how that can affect sales before. I mean, as a reader, I can see where I can be confused when there are two or more books written by different authors sharing the same title. So my question to you, writers, is, do you think about the uniqueness of your book title when naming a book? Do you research it before you decide on it? Or you just simply like a title and go with it?