Paper: The Akamai Network - 61,000 Servers, 1,000 Networks, 70 Countries
highscalability.com
highscalability.com
Op plug: App is http://mynaweb.com/ I just broke the sign up form so email us if you want in on the beta.
There are in fact so many CDNs around now that at least one seemingly independent comparison site[1] has been created.
Also, these services aren't just blanket across your domain or account - you can configure exactly what content gets what treatment based on literally hundreds of different variables. Furthermore, there are ways of having your origin servers send info to Akamai's edge caches that can then be used to make even smarter decisions, per-request.
I agree with other posters - it's expensive overkill for small sites or sites with modest needs, but for those who need maximum control, reliability and performance, I don't think there's any other company that provides it.
We still have not officially launched but this is a barebones website:
extremetcp.com
Let me know what you think. You can reach me at hristo at mainlinenet dot com.
I'm not sure what kind of work they do, but they make a point of saying they don't need much human intervention. So, that might be all.
Though it also reports Rackspace Global Average as 695 ms (91990 Tests)