Argiope aurantia, also known as the Corn Spider, Black and Yellow Garden Spider, Writing Spider or Zipper Spider. It's a member of the orb weaver family. This is clearly a female, males are smaller and have a narrow abdomen. They are considered harmless to humans.

I stepped outside and saw this spider near my bedroom window. I thought about taking a picture, then I saw a rather large insect land in the web right next to her. The spider quickly pounced, and I ran inside for my camera. Unfortunately, it was so humid the lens fogged over immediately; I had to wait several minutes for the camera lens to warm up. By then the prey was pretty much done for.

This is the "wide" shot, I'll be uploading a macro shot with lots of icky detail in a few minutes.