Destroy the Web
You install the add-on to Firefox, visit a website, hit the button and start clicking like mad to destory all the elements on the page. You can then challenge others to beat your score and scores are logged per site.
While testing this I did discover that each add-on for Firefox has a detailed statistics page (well the ones that haven't been hidden do). here are the stats for Destroy the Web.
It then made me wonder what the is the #1 Add-on for Firefox.....
And it's Adblock Plus. A banner ad blocker :) 10,000,000 active daily users! with 64,000,000 downloads. Ouch!
Love the accent. Note: Bannerblog loads so much quicker with this plugin installed.
The next most popular are:
Video DownloadHelper: which helps you download videos from Youtube (handy)
NoScript: for the security conscious
FlashGot: Download all the links, movies and audio clips of a page at the maximum speed with a single click (handy)
I was waiting for a Twilight Add-on to appear but no luck.
So people are blocking ads, grabbing content and being super security conscious. Sounds like the web to me.