If you are an artist - anywhere on the spectrum, from "casual sketcher" to "full-time professional" - and you have an iPad (or to a lesser extent an iPhone), then the two PoseBook By Silver apps are literally the best twenty dollars you will ever spend. End of story.
App Review: PoseBook by Silver (Male and Female)
The extensive gallery of photos of hand poses alone is probably worth the $9.99 per app. (Because seriously, hands are so hard!)
Not to sound all fangirl-ish, but Stephen Silver is one of the animation/sketching/cartooning world's true treasures. He is one of the world's best character designers, but better still, he has the drive and the skills to teach. You rarely see such a powerful combination of "artistic chops and resume" and "amazing teacher" in the same person. But that is Stephen Silver in a nutshell. I cannot overstate his importance - to me, to millions of other artist and aspiring artists, and to the world at large.
I have always envied people who could take proper classes with Silver. He offers many courses online, but they are all out of my price range. Until now.
The PoseBook apps are a pair: one of male characters, and one female. The underlying idea is, "it's a bunch of photos of models striking poses, and you can use them as reference material for your sketches." This alone would be pretty great - the extensive gallery of photos of hand poses alone is probably worth the $9.99 per app. (Because seriously, hands are so hard!)
That's certainly how it started out. But then Silver added in a layer of exposition which makes each of these apps a master class which is suited for beginners and advanced artists alike. He doesn't just plop down the models and tell you to draw them; he tells you how, and where you can go, and pushes you to go even farther.
It's like a Life Drawing class, an online character design course, a collection of reference photos (each one zoomable and from multiple angles), and the opportunity to peer over Silver's shoulder as he works, all in one ten-dollar package. A mind-boggling value!
It's hard to express how much my mind was blown by this app. I had only planned to order one, and to work with it for a while before I decided whether or not to order the other. But after a few clicks, it was clear that there was so much value here, I had to order the second one immediately.
These apps will probably work best for iPad users. You can prop up your iPad and use it as reference material while sketching in a real-world sketchbook. I'm not sure how you would use it to sketch on the iPad itself, so that's something to take into consideration. I'm also thinking that an iPhone's screen might be too tiny, but since you can pinch and zoom everything, you can probably get by. (And you can still watch the videos, which are great!)