Not sure this will work well in Florida yet, but very intriguing for iPhone and iPad.
This free mobile app uses visual recognition software to help identify tree species from photographs of their leaves.
Leafsnap contains beautiful high-resolution images of leaves, flowers, fruit, petiole, seeds, and bark. Leafsnap currently includes the trees of New York City and Washington, D.C., and will soon grow to include the trees of the entire continental United States.
This website shows the tree species included in Leafsnap, the collections of its users, and the team of research volunteers working to produce it.