Various interesting sites I've happened across lately...
Miami: Reflections on the River. You can watch videos about the Miami River, and even make your own to add to the site.
Florida's Lost Tourist Attractions. 50+ homages to roadside attractions that have passed.
Historical Tampa. A Google Map showing former locations of historic buildings, site, and landmarks in Tampa.
St. Petersburg Times' Special Report on Spring Training in St. Petersburg
Spanish River Papers. Available through the Boca Raton Historical Society's website, pdf copies of their journal, dating from 1973 to 1993.