I've always got vases, mason jars, wine bottles, old perfume bottles etc. with something rooting. My thought is "If it holds water, it'll hold a couple of sprigs." A few years ago on DG we had a "Rooting Jar Exchange" which was a lot of fun! I received a neat old soda bottle that I rooted a plant in but the roots ended up filling the bottle and I had to break the bottle to get the plant out. Here's a few of my rooting jars/vases/bottles:
