Lookup canoe or kayak rentals for redfish or snook fishing inshore. Many other species may also be caught inshore. Use Mirrolures (floaters or slow sinkers), 1/8 or 1/4oz. jigs or weedless spoons (gold for redfish). Get a floating bait bucket and 2 dozen live pinfish OR shrimp and tie it over the side of the boat. Use a 6' stringer, tied to the handle of the bait bucket.
Doug
( if you can't have fun and catch fish in the Keys, you just aren't trying..... imo )
*TIP: don't forget to spit on your bait.
Edited to add:
http://search.yahoo.com/search?ei=utf-8&fr=slv8-wave&p=Florida Keys canoe, kayak rentals
http://www.kayakfloridakeys.com/