We've let a spider and her web live across our front door all summer. She's pretty fat. We've actually wiped out her web multiple times when we knew we had front-door visitors coming, or simply by accident (I've walked right through it at least once). She rebuilds quickly.
Her web won't impact the crazy mosquito population we're suffering with this summer, but I think it's caught a few ants trying to march into the house.
We had a spider like that once-- a long time ago when I was a kid living in Georgia. It was gigantic-- a fat brown orb weaving spider of some sort. She made her web directly over the outside of the glass window attached to our patio door. It looked just like a Halloween decoration, but we loved her. She was so big, we could see all of her features, including her eyes. When we tapped on the other side of the glass from the inside, she would bare her fangs and try to bite our fingers. The porch light attracted all kinds of large moths and other insects that would get caught in her web-- almost more than she could handle. It was a real treat watching the spider lunge at the poor things, bit them, and wrap them up like mummies.
My stepdad named her Fred.