Opera has a feature that lets the user create and modify a speed dial page. What is out there like this for the non-Opera user. I can manually create custom portal pages for users but I am looking for something such as an applet that already exists.
This is a browser feature. There are similar add-on or extensions for other browsers too.
Here are some of them:
Firefox Speed Dial add-on
Firefox Fast Dial add-on
Google Chrome Speed Dial Extension
There are also websites providing similar features, e.g. Safari Dial
Or you can create your own Speed Dial Bookmarklet for Webkit Browsers
IE8's new tab (using toolbar:new_tab.html) and Chrome's default page also display similar grid/thumbnails for the most visited sites.
So for your question, unless you really want to implement a much more feature-rich Speed Dial, I'll suggest you use the ones available now.