In the app store, remember the milk is listed as free. Be sure to read the fine print - it is a free trial and $25 a year for a pro account if you want to continue using it. At least they figured out how to keep apple from getting it's 30% cut.

The key features of the app are task management by type of task, priority, due dates, time estimate, tags, location plus a few more. All of your tasks sync to a web server making it available anywhere by default including the more commonly used web interface.

Editing and modifying tasks from the iPhone is very intuitive and allows you to do things like swipe across a task to complete it, date and time pickers use the standard wheel controls or can be manually entered. Even cooler, you can check off as many tasks as you like and postpone them!

Remember the Milk is simple to use, easy to update and modify, and feature rich including options for stuff like email, IM, and SMS updates.