Apps designed to create eye-popping photos on the goA picture may be worth a thousand words. But in the social media age, a photo artfully enhanced by a great app might be worth just a smidgen more.Creativity is the most valuable currency on photo-based social sites such as Instagram, Pinterest, and Facebook; the more eye-catching your posts, the more followers you’re likely to have. Smart marketers offer their followers a never-ending flow of beautiful images—built for sharing or simply for making a strong impression. Consequently, competition for consumer eyeballs online has never been more cutthroat.Luckily, keeping up with online trends is almost always as easy as staying abreast of the latest mobile apps. These tools can turn plain-Jane feeds into screen-bound art galleries. Below, a few hardworking image manipulators ready to jazz up your social snaps.Pocket DesignersCollages a