OK thought seeming as iPhones and iPads are not used in the same way that there should be a seperate thread with apps that people have found that are great on the iPad.
I have found Stanza to be a great ebook reader. Also got to give credit to the NZ Herald for putting a great newspaper app out and giving it away! I know they have said they will charge in the next version but a great way to show people how well a electronic newspaper can work.