Mono, the open source development platform based on the .NET framework, allows developers to build Linux and cross-platform applications with improved developer productivity. Mono's .NET implementation is based on the ECMA standards for C#  and the Common Language Infrastructure.

NDD lists all .net processes running on current machine

With .NDD you can dump all domains of a .NET software

Do you love the computer? Have you ever given a thought to getting an online education? If you can't get enough of the internet, learn how you can earn your university degrees online! No matter if you are old or young, getting an online education is the education of the future! Find out how you can
get College online Grants as well!

MonoDevelop is a free GNOME IDE primarily designed for C# and other .NET languages. The main features of MonoDevelop are:

• Code Completion. MonoDevelop's intelligent code completion attempts to complete type, method and field names as you're typing. The IDE will automatically get the class information from your source code files and from the libraries referenced in your project.

Version 5.0 is powered with Visual Decompiler to build code flow diagrams.

Spices.Decompiler decompiles/disassembles .Net assemblies from MSIL (MS Intermediate Language) binary format to well-formed and optimized source code (6 languages: MSIL, C#, VB.NET, Delphi.Net J# and managed C++). Spices.Decompiler completely integrated into Spices.Net and offers wide range of services to diplay or decompile to files any scope (Assembly, Namespace, Type, Method or selection of these scopes) of .Net assembly.

• Many bugfixes
• Better font handling/painting
• Improved painting
• Better parser/lexer integration
• Updated to NSIS 2.18

xacc.ide is a opensource IDE aimed at mainly .NET development. It has a code editor written in 100% C# code, which is faster than most commercial offerings. xacc.ide blog.

The goal of DotGNU Portable.NET is to build a suite of Free Software tools to compile and execute applications for the Common Language Infrastructure (CLI), which is often referred to as ".NET".

RE-Sign is a tool to help u re-sign .NET assemblys with your own StrongName keypair, and no need todo any manual patching anymore and no need to have sn.exe installed. If u don't have a StrongName keypair file u do need sn.exe to generate one, but I will include a keypair file generator in the next version.

#ziplib (SharpZipLib, formerly NZipLib) is a Zip, GZip, Tar and BZip2 library written entirely in C# for the .NET platform. It is implemented as an assembly (installable in the GAC), and thus can easily be incorporated into other projects (in any .NET language). The creator of #ziplib put it this way: "I've ported the zip library over to C# because I needed gzip/zip compression and I didn't want to use libzip.dll or something like this. I want all in pure C#."

The Express Editions are an expansion of the Visual Studio and SQL Server product line to include lightweight, easy-to-use, and easy-to-learn tools for hobbyists, students, and novice developers who want to build dynamic Windows applications, Web sites, and Web services. The Express products consist of:

JaCIL (pronounced "jackal") is a graduate capstone project to create a byte-code compiler to translate CLI binaries to binaries suitable for consumption by the JVM.

Both the .NET Framework via the Common Language Infrastructure (CLI) and the Java Virtual Machine (JVM) provide for a managed, virtual execution environment for running high-level virtual machine code. As these two platforms become ubiquitous, it is of pragmatic and academic interest to have the capability of running CLI code on the JVM and visa-versa.