The spider in the original post appears to be a Yellow Garden Spider (Argiope aurantia) aka Black and Yellow Garden Spider, Black and Yellow Argiope, Garden Spider, Writing Spider, Golden Orbweaver.
http://www.spiders.us/species/argiope-aurantia/Locally we have what we call a banana spider. The proper name is golden orb-web spider (Nephila clavipes). It is common for these spiders to build webs that span 30 feet across bayous. They are slightly venomous, but not dangerous to humans.
The two species look somewhat similar but are different spiders.
