The problem with node.js, is that you need to run it as a server. Since webbrowsers are considered as client only (for security reasons), you need to find a way to provide an executable version of the nodejs binary to your user.
On FF, you can use something like POW (an extension plugging a webserver inside FF), on Opera, there's Unite, which has his own limitations, but I don't think there are something available natively for the other browsers...