I own a lot of sewing thread since I sew a lot - both my serger and my cover stitch machine uses up to 4 rolls at a time, so it quickly adds up. When I'm at the fabric store, I can never remember exactly which colours, I already own, and more than once I have ended up picking some, that I already had and ended up taking an extra trip to the store to return them. Therefore I have now made an inventory chart of sorts with all of the colours of sewing thread that I own :-) - this will make purchasing sewing thread in the future much easier.