If you want to make an XPCOM component, the first thing that comes to do is to get a UUID for your component.
Here are the two online ones that would just do this job for you free of charge ;-)
I like the first one better, as it allows you to make a whole bunch of UUIDs, and let you pick the number that you think is right for your dream component!
Oh, one more freebie ;-)If you are in a really good mood and have a couple of minutes to spare, why not try to generate a UUID from Firefox itself? It’s got an XPCOM component to do this! How fun would that be? ;-)