I have used it to attach emblems on clothing, cutting it in strips to use up strips of batting, applying a lining to the backs of embroidered bookmarks and to apply appliques to a background fabric.
A thin strip helps hold a hem in place too so you don't need to pin before hand or machine stitching it in place. Fusible interfacing is a handy thing and has many uses where you need stability without the use of pins.
Carol J.