No it's not a dinosaur. It's a Firefox addon which I love. In fact without it I don't do anything in Firefox. What it does is it makes Firefox behave like my favourite text editor Vim. So I can browse internet without touching the mouse. And it is much faster to use keyboard to browse internet than mouse once you get used to it.
Back when I was testing and playing with all those different window managers, after I had set up awesome window manager as my primary working environment. My mouse stopped working. So for about three months I was using my computer without a mouse. Not because I wasn't able to buy a new one, but because I wasn't missing it much to make an effort to go and buy one. And that happened first because of the addon called vimperator. And in Firefox version 3.* I used vimperator without any problems and it was all good. But when Firefox 4 came out I didn't like the so called “improvements” in UI. To be specific I didn't like that statusbar was gone. And vimperator also kept the address bar because now it contained the buttons for addons. So I wasn't very happy with it. And one day when I was wandering in Arch forums I saw a thread mentioning a curious “pentadactyl” and how it was an improvement over vimperator. So I searched for it and installed it and I immediately fell in love with it because it restored the statusbar and addressbar was again gone from the UI. Hooray!