Our application will be serving a large number of small, thumbnail-size images (about 6-12KB in size) through HTTP. I\'ve been asked to investigate whether using a NoSQL dat
Well CDN would be the obvious choice. Since that's out, I'd say your best bet for fault tolerance and load balancing would be your own private data center (whatever that means to you) behind 2 or more load balancers like an F5. This will be your easiest management system and you can get as much fault tolerance as your hardware budget allows. You won't need any new software expertise, just XCOPY.
For true fault tolerance you're going to need geographic dispersion or you're subject to anyone with a backhoe.
(Gravatars?)