IThought's HD MindMapping App on the iPad

IThought's HD is the one MindMapping application I would recommend above all others. The developer sat down and thought to himself, how do I create MindMaps on the iPad? How is that different? And we will talk about OPML in a minute. So you want to make sure that you use one of these that sticks with a standard format so you can go back and forth between multiple devices.