Remember The Milk is perfect for those who love to make lists and keep up with to-dos. It's an application that comes as a downloadable client, a web-based application, and an iPhone app. All of the tools sync together (once every 24 hours with the free version, and unlimited with the paid version), so you can access your lists whether you're at your desk, at a friend's house, or at the grocery store!
When I used a paper planner, I religiously wrote down all of my tasks and lists. Oh, the lists -- I had a slew of them! I was constantly rewriting the tasks I didn't complete on a certain day, or the tasks that recur on a regular basis. Worse than that, though, was that my planner grew to be so large, I rarely took it with me when I left the house. That meant that I frequently forgot those items in my lists. I wasted a lot of time.
I love Remember The Milk because it helps me keep track of all of the tasks and lists I used to keep in my paper planner. I don't have to rewrite a task if I don't get to it today -- it will faithfully show up to remind me tomorrow. I don't have to waste time and gas running errands that I forgot to do while I was already out, and I don't have to go back to the grocery store when I've forgotten an item. Remember the Milk literally helps me to remember the milk!
I can also stay focused by creating several different lists. I have a list for chores, books I want to read, my goals, shopping... all kinds of subjects to keep my life organized.
I use Remember the Milk on the web so I can use it while I'm at my computer, and I also have it on my iPhone to review and update when I'm out and about. I haven't used the download client yet, because I really haven't needed it.
Remember The Milk has truly, truly transformed my life. I'm not getting paid to say that -- I really mean it! If you're looking for an app to help you stay organized and on task, give it a look see!