This extension is called Tab Effect and as the name implies, it adds an effect to your Firefox browser whenever you switch between tabs. Personally, i found this really cool. Below is a preview of how the effect looks like, please click on it to view the larger version: Though some people complain that this effect causes some time delay between tab switching, but i don't seem to have a problem with that, of course there is a tiny meeny time lag. If previously you can immediately view the tab that you are switching to, but if you are using this extension, it will just add a fraction of a second to the transition and it is for a good reason, for the effect to run. Anyway enough of mumbling, i really recommend to you at least try this extension out, it may not be everyones cup of coffee, but who knows, you might just end up loving it like me :). To download please click on this link: Tab Effect to go to the extension's download page