Relatively late addition...
I realize I'm late to the game here, but I utilized some of the backgrounds posted & linked here for the past year or 2... So I'm contributing back to the thread and the OP. With a new, upgraded OS (kitkat), I made my own kitkat themed folder background, and I'm willing to adjust it as needed. This is what I'm currently using and I love it. When I get bored and make a new one, I will definitely come back and add that also. But for now, here is my kitkat folder background for use with Nova Launcher.