I have the cattys from the 1998-1999 catty to the present, and all the minis from 2003 to the present. I use them several ways....
1. I use them when I see older sets retired on ebay or here on SCS to identify the set (if I am not familiar with the name) and the original costs.
2. I use them to look up samples of certain stamp sets and see if I want to case the same or modify it.
3. I love to check the color choices of the sample cards and get ideas of colors combos I do like.
4. My sister and I have all the same cattys and we made little labels with NJ and AB on it. She is NJ and I am AB, and then we sat down and labeled the cattys as to who owned which sets. Sure helps us both and not duplicating sets. Which is REALLY important now that we live next door to each other
(kind of doubles our SU choices you know)....lol.