How I Use It
Remember the Milk is a flexible task manager that I first used in 2008. I really love the interface on the iOS version. It is intuitive, responsive and playful. It stores your tasks in the cloud and has free apps for iOS, Android, Blackberry as well as a web interface. You can sort your tasks by categories you create, an enable geolocation tasks so you remember to pick up milk the next time you are near a convenience store or dairy. You can also share your tasks with others and setup RTM to tweet reminders to you.
The downside of RTM (and the deal breaker for me) is that it will only sync once per day unless you upgrade to the pro account for $25 dollars a year (no educational discount).
I do really like RTM, but it is simply overpriced especially when you consider the number for free alternatives. Personally I do use a paid task manger (Things), but that is because it includes so many additional features and it does not require a monthly or yearly subscription. Otherwise I have had lots of success with Reminders in iOS, Google Tasks, and Wunderlist (there is a free and paid version).