1. Divide the map into several smaller image files and assign hint (message) to each file.
2. Create a Java script that tracks the user's mouse movement and pop up message box when the mouse stays on a position for a predefined period of time.
3. Write a Java Applet that can easily achieves this task providing you are a Java expert.
4. Write a Macromedia Flash that can easily achieves this task providing you are a Flash expert.
5. If the target platform is Internet Explorer, write an ActiveX control that can easily achieves this task if you are an ActiveX expert.
6. etc, etc...
