Unfortunately, if you want to do things with the iPad, you always have to grab it with two hands for the best possible grip. Try and grab it with one, and you would be surprised at how slippery it can be. Then it drops, cracks the screen, and you got a whole new set of problems.
I have seen a lot of solution for this problem like the aptly named Free One Hand or Turntablet. The most simplistic of solutions to the problem of iPad hand is the iSucker. The iSucker is one of those suction cups that you see in the movies, like when the burglar is trying to cut a circular hole in a pane of glass. This is just made for its sticking power, and the iSucker sticks on the back of the iPad awesomely, provided the plunger is engaged.
The end result is a growth on the back of the iPad that is good for grabbing, or even a stand, like you see in the image. It really will come in handy.
If you want to get a hand on the iSucker, it is available on the iSucker site for $24.99 in many colors.