C# and VB .net (higher level languages) tend to be good for n-tier business applications and such.
I find C++ a very interesting language and would like to spend more time developing in it.
What kinds of applications are better suited to C++ applications? Are many windows forms apps (for example) created using C++?
Wall Street derivative trading application. Written in C++ mainly for speed and legacy purpose.
C++ is rapidly losing popularity in the GUI 'forms' area, and other 'front-end' uses.
It is a very mature, and very powerful language (and development environment), but for many people it is too 'complicated' for rapid development; a highly prized attribute when doing front-end development.
Where C++ has retained it's edge, and is still highly respected, is in high-performance libraries in financial markets, simulations, and in video games / high end visual rendering.
C++ is best suited for system programming. For example, creating windows services. Also, traditionally it has been the language of choice for writing high-performance code such as in 3D graphics or scientific applications.
In general, C++ frameworks (MFC, etc) are tedious for creating graphical applications compared to modern alternatives such as WPF and Windows Forms.
I have seen that C++ is used majorly in product development where the dependencies are to be kept to a minimum and you need the installer to be small. Also, if I am asked to write application that rely heavily on APIs or has a tight integration with Windows (like the Shell Extension) I would go for C++ rather than .NET.
Where you need your app to run on more than just .Net
or you need to use existing libraries other than .Net
or you care about performance
or you don't want to rewrite your app for the next 'big thing'
Additional areas where you won't get rid of C++ soon:
C++ is a good systems programming language. It means, C++ is well suited for creating operating systems, language runtimes etc. C++ is also a good choice for writing programs that need to interact closely with hardware. Examples are device drivers, embedded systems etc. One plus-point of C++ is that it brings OOP and generics to the realms of low-level systems programming.
Some popular software written in C++ are the Java virtual machine, MySQL database server, Adobe Photoshop (and many other Adobe products), Maya, BeOS, Google (web search engine, GFS, MapReduce, Chromium), Mozilla etc. Probably that list gives a good idea of the type of software that could be created with C++. Also see this list of C++ applications.