The great iPad

This past weekend my boyfriend and I finally purchased the great piece of technology known as the iPad. I am very excited to explore this technology and am interested in what it all has to offer. I am curious as to what I can do with it, espcecially things related to teaching. I know very little about what is all on the web, including the iPad, except for the things I have been introduced to in this class. I was wondering if there were some apps out there that are the "must haves". Anything else would be great to know. I finally have something apple and hopefully soon in the near future I can get an iPhone.