There's an awfully fine line between having too many complicated photo editing features on a device that fits in the palm of your hand and not having enough tools to get any real work done. Photoshop Express straddles that line quite nicely, thank you, by offering basic editing features, color adjustment, filters, a handful of essential effects and several borders. Best of all, it's free.
Filling up your new iPhone? Just hoping to make the one you already have even better? These are the apps you don't want to be without.