While I've made my opinions of sketchy wireframes very clear, I have to say that Sqetch provides a gorgeous bridge between hand-drawn wireframes and their computer-created counterparts.
The components have a high visual fidelity, while conveying the incompleteness that many designers seek when they use "sketchy" wireframing tools and templates.
The toolkit provides all of the expected GUI elements that most designers would need, including those for the iPad and smart phones.