I'm sorry, but $2,500 a month to run this site just seems high...I'm not sure what technology pud used to create the site, but it'd be interesting to know. I'd love to see my own sites get this much traffic, but damned if I could really afford to carry the success for too many months. This is where I really think the whole Rails (not saying he used rails...just using it as an example) argument of cheaper development costs but higher server costs breaks down. For the single entrepreneur, and app implemented in Rails versus one in a much faster/resource-friendy (PHP? Java?) framework/language could mean real, significant, insurmountable costs.

Of course, I could be wrong, and I'm sure someone will throw out the rails-is-not-the-bottleneck-the-database-is argument, but I recall reading an article about the gentleman who wrote plentyoffish.com in an unorthodox fashion with C#, and was able to run it for some time successfully on his home machine, then on one physical server. I think this would likely be impossible with rails.

And I say this as a rails fan/developer...