Josh Rose is a PhD candidate at Duke University in North Carolina. His home page is a good starting point for serious students of odonates (dragonflies and damselflies).
(That page may disappear at some point, as Josh is no longer at Duke.)
Giff Beaton's Dragonflies and Damselflies (Odonata) of Georgia
Extensive site with excellent photographs, descriptions of flight dates and occurrence in Georgia. Beaton's site also has Robber Flies, Syrphids, and other organisms.