Popsci: “You’re hemmed in with physical clutter, piles of stuff you don’t really need. This doesn’t just get in your way, but also takes up room you could be using for new purchases. But figuring out what to toss and what to keep, and then following through, is incredibly stressful. These apps can help you organize, digitize, and generally get rid of junk—and maybe make some money while you do so…”