Admittedly, I had a difficult time with this one. Aside from the obvious fact that this was a crop duster of some sort, I had no idea what make or model this airplane was. So I turned to my friends on Twitter. Within minutes of posting the question and a link to the photo, I was headed in the right direction. Thanks to @replies from @pilot2b, @bgwickham, and @Blackprojects, I was able to determine that this is an Air Tractor AT-802.
There were two of them on the north GA ramp at Melbourne on the day I took this picture. I bet THAT is a fun airplane to fly.