Have a small collection of the normal pieces and a few little odd ones. But I don't really have a place to store them well, so a plastic tub under a counter is one place and the oven is another. All but one piece is modern Lodge, the other is a '60s no-name-on-it Wagner we got from my wife's mom. Recently when we were at her place she showed me an old Griswold she picked up for pennies. (!)
But yes I use them on my grills whenever I can, but despite trying a lot of different meats and some veggies, haven't actually made much that required a CI piece yet. Looking to rectify that.