May2013 - We have now released the Visual Micro plugin for Atmel Studio 6.1 which is based on Visual Studio 2010 and is free.
See our beta downloads list and forum for more information.
Visual Studio Pro and Ultimate Alternatives
In March, Microsoft ended the free program that provided Visual Studio Professional Free for 3 years for Arduino programming. Now (beta) we can use the Atmel Studio 6.1 (may 2013 version) of Visual Studio for free.
This page previously described Visual Studio free offers which includes VS Pro for free. Microsoft have withdrawn some of these offers but things change, it is worth looking around to see what "sparks" programs might be available.
Here is a summary of what we think might still be available...
Bizspark - Free VS Ultimate for companies younger than 5 years and less than $1m profit p.a.
Dreamspark - Free VS Pro for Students
If you are looking for a full version of Visual Studio Pro or above Microsoft often have a preview version of their latest and greatest available. Right now the VS Pro 2013 works okay for Arduino development and might also work for your purposes such as C# etc.