This has to be one of my two favorite things this year, to give or to receive. I purchased one for myself a few weeks ago, and I LOVE it. What is it? A case that has a built in battery for your phone. It doubles the battery life of your phone, so if you have kids like I do, that hog my iPhone and play all the games and drain my battery, this is a life-saver. It comes available for the iPhone, Blackberry Bold, Blackberry Curve, as well as the iPod Touch.
This is the case I have, called Light Copper Checkered. These battery cases come in approximately 45 different colors/patterns. The inside is lined in a soft leather, and it feels very well made.
Standard case in Pink Lizard
Standard case in Tan Snake.
Standard case in Stingray. I saw this one and it is really great looking in person.
You can sync your phone and charge it without ever removing it from it's case. I found it took one day to get used to talking on the phone with a case on it, but after one day, I never thought about it again. Also, the phone just slides out in 1/2 a second if you don't want to talk with the case on. Made by SaFPWR and available
here and
here.