This is a really cool video describing Ubiquity, a Mozilla Labs project. In a nutshell, it extends FireFox (and I guess possibly other browsers) to let users create mashups and use them fairly easily in daily tasks, like sending a map to someone. Check out the video here, http://www.vimeo.com/1561578?pg=embed&sec=1561578 or here http://labs.mozilla.com/2008/08/introducing-ubiquity.

If you're still interested, which I think you will be, download the FireFox add-on.

From the post http://labs.mozilla.com/2008/08/introducing-ubiquity, "Install the prototype and you'll be presented with a tutorial to get you started."