Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Orb Weaver? - Argiope argentata

Orb Weaver? - Argiope argentata
Oak Canyon Nature Center, Orange County, California, USA
June 28, 2008
Size: tiny, a few mm

We would suggest,
based on the pattern and the bumps on the front of the abdomen, Argiope argentata - Silver Argiope in the guide here. For example,

Silver Argiope, seconded
I've shot them in the area.

Web and pose are typical of genus Argiope. I'm not sure whether features are available to identify to species at this size, but you might browse that section for a possible match.