Most low-level languages support this, references in C++, pointers in C, ref keyword in C# and Dlang, and so on. It's mostly higher-level languages that do not support such things because it's in the VM semantics that dictate how objects are passed (i.e. in Lua tables are passed by reference, non-table values are passed by copy).
Great point. I, was mistaken; the languages I've used are of the higher-level variety that don't have this feature (And C, which doesn't really have this feature; I don't think that pointers are nearly as nice).
