Jancruz,
How long will you be in Amalfi, what else do you plan to see or have seen?
There are many many options for an afternoon in that area. But I guess it depends on where you have been or will be going, what you like to do, what season it is.... The distances are not far, but even with a driver, the going is slow on those roads. In the summer, I would suggest staying close to that area... or else you will be all day on the road.
ONE IDEA: Why not take a boat trip? Ravello is high up in the hills, but if you want some variety from views of the water and car rides, I would suggest getting out on the water. You can do that from Amalfi and Positano at best, although from other towns (the smaller ones), you will probably have a few (but less) options to do that. I think the views from the water are not only gorgeous, but fascinating.
Also, as this section of the board is "Rest of Europe", I would recommend reposting this in the Italy section of the board.
"Many a trip continues long after movement in time and space has ceased."
(John Steinbeck)