Social networking isn’t just about finding out what your friends are doing–it’s also for saving money. Become a fan of Wicker Park boutique Hejfina on Facebook and you’ll get a code for 25 percent off your first order on the Web site. Then your only problem is deciding what to buy. I’d go for the laser-cut earrings of precious metal by Aesa Rumble or a classic men’s polo by APC.