Cocoa uses Objective-C, C++ and Java as of my knowledge
Cocoa does not use C++. You can access the Cocoa framework from Java and Objective-C, but that doesn't mean that the framework makes "use" of them. Cocoa is implemented using Objective-C and while there is a bridge to make it work in other languages like Java and C#, it's usually far more hassle than it is worth. The reason for this is because Cocoa makes heavy use of Objective-C constructs (like Categories) which have no real equivalent in other languages.
In Mac OSX, I think, you have two ways to program - one procedural way Carbon and one object-orientated framework which is Cocoa
In addition to that you can use:
- C++. There are many GUI libraries open to you, like Qt (not Quicktime) and wxWidgets.
- Python. Using bindings which allow you to use Qt, wxWidgets, and Carbon.
- REALBasic which is quite a nice application development suite, based on the BASIC language.
- C.
If you want to make simple command-line tools you can use ANSI C/C++
and Objective-C, Perl, Python, Java, and pretty much any language you can name, there is a compiler/interpreter for OS X.