Someone mentioned these to me and I'm wondering are they still available in Italy (I read somewhere that they weren't) and how do they work?
They were available in several countries but apparently no longer are, unfortunately. You could buy a pass that was good for a fixed number of kms of travel within a certain time frame. You filled in you departure and arrival locations and the conductor on the train subtracted that distance from your balance. You could even use the same pass for more than one person, they just took off the kms for each traveller.
Yes, sadly discontinued. The Kilometer Pass was really the only pass that made sense in Italy, probably reason enough to discontinue.