Speed Dial is a feature first introduced by Opera almost four years. It is basically a grid of the top websites you visit. From my experience, this is a very convenient way to get to my favorite websites after firing up the browser. This feature has been adopted by Google Chrome as well. Recently, Opera added more features to its Speed Dial by introducing Live Speed Dial.
Oddly, Firefox has not yet adopted this feature. According to the roadmap for Firefox 9, though, that is about to change. This is what the road map for Firefox 9 says:
rest here