CSharpJavaMerger Framework is a framework that enables you to write one set of code which can be used both by C# and Java. CSharpJavaMerger provides common interfaces that can be used both by C# and Java.
Grasshopper is a Visual Studio-based SDK and patented .NET to Java converter that enables you to run .NET Web and server applications to run on Linux® and other Java-enabled platforms.
NET2Java a new technology that helps you take an application written in Visual Basic or C# to the .NET platform, and translate it into a program written in Java source code. Right now its available through a NetBeans plugin that's included in the distribution files.
jsc is a decompiler or a cross compiler if you will. It is not a source-code parser nor an IDE. It is a command line utility like any other compiler. jsc was originally an anagram for csharp to javascript.