I bought the factory cup holders that snap into the holes in the side vents, which don't allow the can or cup to spill nearly as easily... and these keep cold cans of coke cool when the a/c is on.
One must have those little holes to use these though, or be brave and use a drill bit to create them where they don't exist.
Jeff (Tool Pants) said that the original 1997's came with them as part of the car and they've all disappeared when resold because they can be removed and stowed.
I like mine and glad I bought them. Weren't easy to find though. Got them from a guy in Germany who had some old, new stock in the Porsche bags with stickers on them.
I did find them at eagleday...
http://shop.store.yahoo.com/eagleday/inac1.html
Pic is attached so you can see what I mean.