The iPhone App, developed by Elepath, allows you to organize all those little things in life you would forget otherwise. "A strange new restaurant. A book with a nice cover. A far-out dancer."
You can already find quite a few To-Do apps in the AppStore which are supposed to support your personal life. However, what makes Thinglist special is its simplicity, user-friendliness and great app design. In my opinion, that justifies the price of $0.99.