In the end it all boils down on what you're building. If you've done your fair share of programming (C, C++, Java, PHP, Python, Ruby) then you just go with the tools that are best for the job.
Would I write a complete web service in C? Probably not. Would I write a fast image manipulation/modification library for that specific website if needed in C (or C++)? Probably -- because I like the performance gain when I'm converting 10.000 images.
I love the fact that you can just build components in different languages and then glue them together so you can build awesome products.
10,000 images is not over the break even point yet (unless you do something really hard resulting in a runtime significantly larger than what it would cost to farm out that job to a bunch of EC2 instances, it's all about the question whether your time is more expensive than the cost to rent the hardware to do the job).
It starts to pay off when you write that package either as a service with a large number of users or if you make a general purpose library for inclusion in lots of other programs, especially if they are written in other languages.
Would I write a complete web service in C? Probably not. Would I write a fast image manipulation/modification library for that specific website if needed in C (or C++)? Probably -- because I like the performance gain when I'm converting 10.000 images.
I love the fact that you can just build components in different languages and then glue them together so you can build awesome products.