Most National Wildlife Refuges were established to protect wetlands for migratory birds although some were established to protect the habitats of endangered species. Of the ones that allow public access, facilities and activities vary. For instance, some are day use only while others allow camping and some prohibit motorized boats but allow canoeing. The ones listed below do allow public use.
 

St. Vincent St. Marks Lower Suwannee Crystal River The Cedar Keys Chassahowitzka Pinellas Egmont Key "Ding" Darling Key West National Key Deer Great White Heron Loxahatchee Hobe Sound Merritt Island Lake Wooddruff

The U.S. Fish and Game Commission, which maintains these refuges, has a listing of links to the refuges where you can find out much more about them.
 
Information about some of the refuges is also available via the Florida Fish & Wildlife Conservation Commission's search engine, which contains information about many other wildlife viewing locations in the state as well.