I just discovered this gem of a product (or at least it looks like a gem, since I haven't tried it yet), called Inkling by Wacom. It gives you the best of both worlds : The ability to draw on paper and have it recorded digitally so you can tweak it on the computer without having to essentially start from scratch. You can even record your drawing in different layers!
This little portable machine currently retails for $200. It includes a digital pen, a rechargeable pen battery, a pen ink cartridge, a charging case, a receiver, a rechargeable receiver battery, a usb cable, four spare pen ink cartridges, and Inkling Sketch Manager Application and a guide.
Inkling fascinates me. It's so futuristic. The online reviews seemed rather positive. So it's going on my wish list as the first item of 2013 :)