MAKE SURE YOU ARE NOT ON "FREE"/SHARED HOSTING. Yeah, your package sheet may say you get 2TB bandwidth, but realistically, you have something like 30GB before they'll cut you off. Sorry, that's how the Internet works. If you have hosting, please make sure your bandwidth is actually alloted to you.
That being said, if you want to be a mirror, go ahead and reply to this with what you plan to mirror, what your bandwidth cap is, and the physical location of your server. I'm thinking of either making a big regional mirror list or setting up a round robin dns to distribute traffic more evenly.