Years ago, finding La Roche-Posay sunscreen was nearly impossible in the States. Because its lightweight texture was so unusual, I used to wheedle friends into buying some while overseas. These days, the brand is readily available at dermatologists' offices and drugstores alike, and it's just launched another year of its SOS — Save Our Skin campaign. Its aim is to educate people about the dangers of UV exposure, and part of the endeavor involves a free iPhone app called My UV Check. The app uses location-based services to assess the strength of UVA and UVB rays — the ones that cause skin to age and burn, respectively. If you're the kind of person who needs convincing when it comes to wearing sunscreen, it's well worth a download.