Huge difference, C++ is a real and very powerful programming language. C# is like visual basic with c-like syntax. As a rule, you only get to use c# on the .net or mono platforms. For solid cross platform application development, c++ is better than c#. Although Java is better at solid cross platform application development than either of them.
To answer the initial question:
At the moment I use php/mysql, Java/JSP/MySQL, Visual Basic 6/ASP3, Flash/Actionscript, and c++ in my programming projects.