I never had an iPad, but a friend who used to have one was using Paint Shop Pro and doing some designing, that was a long time ago, but I think you could use Photoshop, maybe a portable one that doesn't take space, memory, and is very light, I have one that I use sometimes in my desktop and is CS3, it is old, but when opening my photoshop is a whole ordeal, and I need to scrap a small page, make a banner, resize, etc...CS3 Portable is a good choice, and it is free if I am not mistaken.
Here I found a link:
Adobe Photoshop CS3 Portable.zip (48.16 MB)
But I don't have any information that I can give you besides that. But you can scrap without any problems here.
I know some people used to download this one for Cell phones.
I hope this helps.