Tick it Off
Is there anything the iPhone can't do? Wait.... How about making to-do lists? This plain application let's you do that now.
If it's your shopping list or a list of chores or your New Year's Goals. All this can be done and examined any time you want to. As soon as a task is done you can tick it off.
If you want to see how many tasks you have left without entering the program you can switch the icon badge on in the iPhone Settings menu. Also you can switch on the option "Shake to delete", which enables shaking for deleting all done tasks.