Sometimes, it's hard to remember a world before smartphones. Whatever did we do when we didn't have GPS in our pocket or could check our email on the run? (Answer: we missed out on answering several important, time-sensitive messages and also got lost a whole lot.) In addition to maps and email, when it comes to leading a busy, on-the-go life, certain apps are downright essential. Here are our picks for apps that make our lives more convenient, safer and loads more fun.