Is it legal for an organization to use my photo on their website?

You’re dealing with FL Statutes 540.08, which prohibits the unauthorized use of someone’s name or likeness.  However, as with any statute, there are several factors involved.  I would be interested in whether the photograph is just of you and how it is being used.  Essentially, my advice boils down to making an appointment with an attorney to review the site and the facts.  If this site is in violation of 540.08, you not only have a cause of action to enjoin the use of the photograph, but also to recover damages such as a reasonable royalty for its use.  I wouldn’t wait around on this – you may very well have a case.