I save the plastic lids from cottage cheese containers, yogurt, etc., to cut templates for quilting designs or whatever else you need a template for.
I use non-skid shelf-paper under my sewing machine to keep it from vibrating and walking away--mainly to keep it from vibrating. It's much quieter now.
I use plastic tubs that greens come in for storing leftoever scraps of fusing medium, stabilizer, and anything else I can think of. Fat quarters too.
I use paper towel tubes for things that are rolled up, like my leftover Invisigrip, or leftover sheets of fusing medium. TP tubes are good for wrapping bindings around for storage.
Like everyone else, I use a wooden skewer for a stilleto.
I keep old needles and bent pins in empty prescription bottles until they're full, then throw them away safely.
I use the tape-style Post-It stuff for repairing torn areas on paper-piecing patterns. You can write over it. It behaves more like paper than scotch tape. You can find it at Staples, but apparently, nowhere else.
Also, I've used skewers to keep the tops of small quilts rigid so that they can be hung from a ribbon attached at the top corners, scroll-style.
I've used pop top rings for small quilt hangers. Just sew them to the back like any picture hanger.