You've probably already heard about those Masai Anti-Cellulite Sneakers, but for summer, you're probably better off with the MBT Barefoot Sandals. These shoes are supposed to make the flat concrete more like bumpy natural terrain, which tones your muscles as you walk.  Some wearers also claim that regular use has greatly improved their posture and rid them of back pain.  In any case, I would love for these to become the new "It Shoe" since I would never be able to walk in Manolos, even if I could afford them.