A lot of people who say "I have no idea what I would do with one" literally don't have an idea and just haven't been shown what can be done. I find plenty of uses for it at work, especially when I want to have a certain document but hate keeping track of the paper versions. Put a PDF in iBooks and shazam.
I can also watch a crapload of soccer on the MLS app. It's about $30 cheaper than subscribing to the TV package for everything, plus it's all portable.
Don't even get me started on the Kindle app. If it had an odometer, I probably would've broken it.
One last thing i have used it for is a pseudo notebook. I typed up a game story using only it and my iPhone. I used to use a MacBook Pro, but the iPad is SO MUCH LIGHTER. If I did that more often, I might consider a MacBook Air in case I needed an actual computer for various reasons, but it works well for what I do.