Many of the stuff that has a lot of legacy code laying around is C++ or plain C (this would include the Office suites). When the Win2k source leak happened years ago, much of the APIs were C++, though the kernel remained in C. I'm not sure of more recent tools, but I'd imagine that, with the shift to the .NET framework, a lot of new stuff in the Windows world is in C#. (Also, "Visual C++" is an IDE, not a language.)
In UNIX land, C is king. Most apps and core OS code are written in plain C, with C++ taking the back seat. Mac OS X, being UNIX, has at least an underpinning layer of C, with the user side of things featuring lots of Objective-C (though some is still C++, or at least Objective-C++, such as the current, pre-Snow Leopard version of Finder). Then again, Objective-C is basically C with Smalltalk-style objects (it's a true superset, unlike C++), so you could argue that's all C, as well.
Some popular *nix apps are C++, though. Firefox is, and since WebKit is as well, I would assume that Chrome follows suit.
Hopefully that helps. To put it simply, most apps seem to be in the C family :)
You can make something like MS Word in Perl or random interpreted language X. One of the primary reasons you don't ever see it is because it would run like molasses.