I come from a web developer background, so I'm fairly familiar with PHP and JavaScript, but I'd eventually like to branch out into other languages. At this point, I don't have a particular direction or platform that I'm leaning toward as far as learning a new language or what I would use it for, but I would like to learn a little bit more about programming languages in general and what each one is used for. I've often heard (and I agree) that you should use the right tool for the job, so what jobs are each programming language best suited for?
Edit: If you've worked with some of the newer or more obscure languages, please share for those as well.