I purchased this product: Book Holder - The Revolutionary New BookGem for use with my Kindle and it's turned out to be the best $14.95 that I've ever spent. It works fantastic with the iPad, it's portable, and very stable. I picked mine up from Amazon.
Nice find. I'm thinking of picking one of these up too. I'd be really curious how stable it is for resting the pad on an armrest while travelling in the car.
My grand daughter uses it on the large back seat arm rest to watch movies and read books. It doesn't even bobble. The fold out support legs in the back have a wide stance and rubber feet.