I am a huge fan of the firefox update scanner as previously blogged, in that it saves me a lot of time (and hurts when its not there!). Recently I’ve discovered that you can backup and restore or transfer the websites you are monitoring with ease in a remarkably simple way that I coudnt find anywhere on the web.
All your websites being scanned are stored in your bookmarks, so if you backup all your bookmarks using the bookmark manager in firefox, it will save them all. you can then import them onto the new machine (in my case my new netbook) once you have installed the plugin on the new machine. And hey presto, you are monitoring the same websites on the new machine. If you really want mobility, email the exported bookmarks file to your web email account, and you can install it on any machine anywhere at any time that has firefox.