No, no one else ever uses my Xbox. I actually have two 360's, one in my bedroom and the other in the family room. Why do I need two? Well because they break sometimes plus it's nice to just play in my room too. Or I can download movies and tv shows at night and watch them in bed. I do a bit better with keeping track of MS points than I actually do with PPV. So that's the best way for me to watch movies. If not I can post the pdf of my $202 cable bill, but then you'd know where I live and all that kinda stuff.
Would I let anyone go on it? If by go you mean piss then maybe. I don't really know why but something about that would be cool, I'd have to get it on youtube or something like that though. I wouldn't mind my brother getting on the one, I live with my brother btw so that should answer that question. However I'd be sure to make him a profile or let him use my other xbox live account and change the tag to something he liked. I'd also put that on a seperate hard drive so he didn't mess with my stuff at all.