My iPad serves a couple purposes:
Entertainment: All of the things you described. It's my newspaper, magazine, book, TV when I travel, games, web surfing, in-flight entertainment system, etc.
Work: I work for a technology company that is, ironically enough, kind of ass backwards when it comes to getting their employees the tools they need to do their job. My department could REALLY use photoshop, but it's not on the approved software list. So I use Photoshop Touch on my iPad to do all of the photo editing that I need. I also keep PDFs, PowerPoint, Word and Excel files on there for reference (which sync to my iPhone so I always have them with me). Note-taking in meetings, creating and editing training presentations.
My iPad is pretty much my right hand.