I've read that some tribes used certain species' webbing as fishing nets. If that isn't a testament to the strength of this material, I don't know what is.
Anybody remember the Spider-Goats?
Side-Note: The physical properties responsible for webbing's strength are two-fold: an outer system of inter-locking crystalline protein components and a fluid core that distributes tension along the length of the entire thread. The fluid core reduces stress in any one area of the thread, and the interlocking components make it such that if a few fail under stress, it won't compromise the strength and integrity of the thread overall. That's how I remember it, anyway.