As a replacement for C or C++ (except 3D games where the choice of language is dictated by the engine). Kernels, databases, CLI programs, toasters, native code Python modules, etc.
As a replacement for Go if you want a comprehensive type system instead of a skinny one.
I use C++ for backend business servers and web services in particular with stellar results performance wise. Modern C++ along with the STL and loads of 3rd party libs makes rapid development of servers piece of cake.
For browser based applications (they're all single page web apps using json based RPC) I use cpp-httplib and rapid json. I use other as well but do not really want to get into details here. The ones I just mentioned should get you up and running in no time.
