Ponte Vedra-based realtor Krista Fracke has a Google-maps display of FCAT scores for all of the counties in Florida. When you visit the FCAT scores page, click on Polk to get a closer look. The image below is almost all of Polk County.

The standard Google-maps interface is there. You can zoom in, pan-around, etc. The image below is a close-up of the Winter Haven area.

Clicking on one of the pins will give you the details about that particular school, including previous FCAT scores. Shown below are the details for Wahneta Elementary.

Thanks to Joey at Urban Jacksonville for the tip.