Many graphics tablets have mouse-like devices (alluded to above) called
pucks, and they can be set to relative mode (work just like a normal mouse) or absolute mode (like a stylus). They often have a loupe to allow precision work in absolute mode (the crosshairs of the loupe are the active point), so they used to be really common in CAD studios.
Wacom has had this for years and years, well before the Intuos line was ever released. This technology has been around since the 1970's, IIRC. I know for a fact that Wacom has had it since at least the early 1990s, when I got my first graphics tablet (for which Wacom offered a puck, though I never got one). At least now, Wacom only supports picks on their biggest graphics tablets, as best I can tell. Their website is really unclear on the matter.
That said, for ordinary use, a puck is fantastically annoying unless you have a really big graphics tablet, because otherwise you're limited to a small area. Big graphics tablets are 'spensive...