Google Maps overlays with mouseOver hover events

So, I've now created a map, with overlays. Now the need to create mouse over events so that people can interact with them.

Here's some places I've found information:
How to make a map with overlays
How to create an event on mouseOver -> with reference to this post
A similar post, but different solution
Not sure if relevent, but a mouseover tooltip for markers


Some docuemtnation on overlay types and Map Type registry

Google maps overlays

I'm going to start a project which involves overlaying different maps from past, present and future maps. My primary thoughts involved utilising Google maps API for this.

Looks like there's quite a bit of info. Here's some links:

• Getting Started
• Simple Overlay example
• Ground Overlays
• Info on Overlays
• Showing and hiding Overlays

Notes:

Some limitations

Stated in the beginning there are limits to the free use of the API. This is 25000 map initialisations per day, which I consider very high.

Not sure how many overlays you can have, and hopefully control which ones are on and off using sliders and buttons. - Yep, above. "Showing and hiding Overlays"

Half way down the page on Info on Overlays theres a nice example of Animating Symbols