Wacom, the company best known for their tablet and stylus, has developed one of the best “how did we survive without this” technologies to hit the digital illustration and design professions in years. The Inkling (the cute name may be too cute) is a pen and receiver combo that records your pen strokes into a digital file. The file can then be easily imported into Illustrator or Photoshop for further tweaking. What sets this product apart from sketch-and-scan solutions is the way it uses pressure sensitivity in the tip to record how thick the lines should be rendered after you import the data. Additionally, and this is the cool part, it keeps your strokes as vector lines. Bring your sketch into Illustrator and freely tweak and adjust using the bézier tools to complete your sketch process.
Check out this link and this one for the company’s own examples.