remix.kwed.org offers torrents which I think does help with this. I grabbed all the files from the torrents. Only took a short while (and then I seeded for a while too).
Having multiple mirrors though can help in these cases. With exotica we host the files on ftp (which is easy to setup with bandwidth controls), and then redirect to a random mirror from the website. Those that want everything tend to choose a mirror, but with my mirrors for exotica there are connection limits, so their downloading won't affect others.
I find most problem on my site are from bad bots, or botnet attacks where I have 20 or so machines connecting to the site at the same time wither trying to submit forms, or just causing high cpu usage (which I try and reduce with some iptables rules)