A TV on your phone, the selection isnt amazing but 99% of the time you can catch channels playing back to back episodes of Big Bang Thoery, 2 and a half men, Scrubs and Los Simpsons (Spanish dubbed Simpsons, yes I know).
iPhone to iPhone calls through 3G or Wifi,
Better quality than skype and tango, no video yet but they add an IM'ing serivce to it in the last update.
Take photos of documents/papers, the app auto corrects the colors then cuts the extra bits beside the paper then you have the option of saving it in many different formats, and yes pdf is one of them. Very helpful for students. And you can use it to take more than one photo at a time so emailing yourself an 8 page assignment from your friend as a pdf can be done in less than 5 minutes.
You enter a song or artist you like and the app keeps playing songs
Cool feature: Caching stations, you can cache a lot of songs for each station to playback offline, like iTunes but free. available in North America only.
Update: You can get the code for a free month of Slacker Radio Plus by liking their Facebook page
My favorite app so far in 2011, Remember when you needed Photoshop skills to stitch images together and make panoramas ? well.. watch the magic..
Few weeks of taking panoramas, cool but what else ?
Besides the built in functions to export them photos, you can use http://www.dermandar.com/ to upload panoramas and get the curved view instead of just panorama images.. just like Google Street View, your images will turn up Something like this