CloudFlare is a very nice service for that. As an example you can read that blog post: http://blog.cloudflare.com/moog-music-staying-online-when-go...
I don't think they'd let me stay on their stated $20/month plan.
Just checking the blog post, they only pushed 182GB total.
We run 1.75TB per day!
Edit: Checked it out, they go as low as 0.03/GB which might be feasible.
It might even be disingenuous to call CloudFlare a CDN at all. They are really a web application firewall and app delivery service.
I prefer the safety of knowing that my interests and my CDNs interests are aligned.