Can spiders use hanging anchors to make webs?

I've noticed a few spider webs around my house which seem to span incredible distances. The webs are attached to a tree or some other object horizontally, but vertically there is often a leaf, twig, in one case even a small pebble, which is attached to a line supporting the bottom of the web. The object in question is not laying on the ground, but hanging in midair to keep the web taut. Anyone seen this before?