You will find links to Florida county mailing lists here: http://lists.rootsweb.ancestry.com/index/usa/FL/
You may also want to subscribe to the FLORIDA list at RootsWeb/Ancestry.com. Please read the list guidelines first. To subscribe, simply go to: http://lists.rootsweb.ancestry.com/index/usa/FL/misc.html. You can subscribe in either List or Digest mode.
Or for Mail Mode, Address a message to:
Don't sign the message and Turn Off signature files before submitting message. You will receive a welcome message with instructions and the address you will use to post messages. Keep the welcome message -- you may need to refer to it when you need to temporarily unsubscribe.
Florida County Message Boards
Miscellaneous Florida Message Boards
Bonus: How to Write a good query