You can have a lot of fun with your site by using Java Applets and JavaScript.

I am only offering an example of each and some links for both. Follow the links and learn more than you ever wanted to know.

Java

I obtained the above Lake Applet from The Java Boutique. They have a long list of fascinating visual applets on their Visual Effects Page.
Author: David Griffiths 

JavaScript

You may want to use a JavaScript Drop-Down Menu for connection to other pages at your site; however, it is best to also have text links available for those whose browsers do not support JavaScript.

I obtained the JavaScript for this menu from JavaScript Made Easy. They have a large collection of interesting JavaScripts.

Java Sources:
The Java Boutique 
Donna's Retreat/Tutorial (I get Java errors there, but it is an informative site.)
Beauty of Terra (No information; just interesting applets.)

JavaScript Sources:
Cut-N-Paste JavaScript 
JavaScript Made Easy 
JavaScripts.Com 
Voodoo'S Intro to JavaScript 
Webpedia