I'm addicted to making banners and avatars for my Etsy shop. It's an unfortunate addiction, because it means I'll never know if consistency in your shop's look increases sales. But I love playing around with fonts and colors, and I can't imagine keeping one look for too long.
I made a new one yesterday to showcase my current bestseller, the Snow Blossom Earrings. The ten inches of snow we got over the course of the day clearly influenced my work!
Of course, I'll probably change it again in a few months. 'Cuz I'm fickle like that.