A couple of months ago I asked for suggestions for a CDN that a library
without its own web server (other than our OPAC) might use to deploy image,
LibGuides, Serials Solutions A-Z journal lists, etc.
We're a small institution and I have just a handful of files I needed to
deploy, so I figured that using a CDN could be much less expensive than
contracting for a full-fledged web hosting solution. I weighed several good
suggestions sent to this list and decided to give Rackspace Cloud Files 
a try. Pricing is 10 cents/Gigabyte/month.
It doesn't have a true nest folder file structure, but if you use
Cyberduck, which supports the Rackspace API , it represents the
directory structure of your original local repo in the URL -- e.g.,
I didn't purchase anything but Cloud Files, so I don't have access to
Rackspace CNAMES to give my URLs more friendly names (and campus IT isn't
interested in providing that service for us). I decided this was not a
problem on the whole.
The system has been very fast and stable, with none of the intermittent
outages I experienced when I was testing the idea by hosting some of these
files on my hobby website on Bluehost.
The only gotcha is that if you need to upload a file, there is some latency
for changes to propagate across the CDN. The Rackspace technician I talked
too was surprised how long an old copy was hanging around after one of my
updates, but we concluded that, ultimately, that's the proper function of
the service (at least on this CDN). You can speed things up by deleting the
original and re-upping it, but changes are not instantaneous.
After 2 complete billing cycles, we've yet to have enough traffic to
generate a charge. This surprised me, since I thought there might be a
minimum usage charge hidden somewhere, but we've not seen any to date. I'm
not anticipating this situation will change drastically. It will take quite
a bit of traffic for us to hit the 10 cent mark.
I'm pretty happy so far.