Last week in watercolor class, after a demo of using the grid system to transfer a drawing from the source to our painting surface, I tried copying a photo from my iPhone onto my paper, and complained to teacher Jane Voorhees that a grid over the iPhone would have made things much easier. And wouldn't you know, Jane immediately replied, "There's an app for that!" She was referring to Accudraw, which I immediately downloaded and used to do the job in a flash.
Accuview looks pretty cool, too. I think I'll try that next.
And of course I did this: