Apple users are passionate. Windows users are not. Mozilla Firefox users are passionate. Internet Explorer users are not.
I'll stay away from the almost cliché example of Apple and instead use Firefox.
Mozilla recently announced Firefox 3 will be launched shortly and have decided to involve their powerful consumer following. On what will be Download Day, they will be trying to break the Guinness World Record for the most downloaded software in 24 hours.
You can actually pledge to download the software, where they will then send you a reminder email on the day. A fantastic idea and at the moment they already have 672,214 pledges. Not downloads, but pledges.
I think Internet Explorer might be in trouble. In fact, I wonder how many people would pledge to download their latest version?...