I am fascinated that no one uses Objective C on the back end. Fast, low memory, quick to code in, high-level-enough, a mix of static and dynamic typing, and no garbage collection. Also plenty of expertise you can hire for, maybe already within your company. I think if Obj C had a good story for deploying on Linux (and not losing modern features like ARC), it would make sense to use it, so we'd see sites doing it and open source tools like a good webapp framework. It is because you would need to run OS X servers? (And is that even true?)