I have always struggled with keeping track of everything I need to do on a weekly basis. Between church, family, and life, I always have more to do and somewhere else I need to be. So, for me, technology has helped me become more organized. I have tried several task management systems in the past, but I have settled on using a service and app called Any.Do. It just fits the way I think and work, and it has already been a big help to me in scheduling my week.
Any.Do works by organizing your tasks into either folders or categories. The categories are Today, Tomorrow, Upcoming, or Someday. The app works on my phone and my computer, and it stays synchronized. It allows you to set recurring tasks, reminders, create sub-tasks, and even share tasks and attach files and folders using their premium service. They do offer a free version, but the cost of the premium version is affordable. The app also has a cool feature that helps you plan each day. You can set reminders and choose what you want to accomplish each morning. The best part is the app is simple, clean, and has a great user interface. It just works like it should. Here is a screenshot and a video to learn more about the app.
(note: I have also tried Wunderlist, Remember the Milk, Google Calendar Tasks, Producteev, and Astrid, but my favorite by far is Any.Do)