I am a solutions developer and my development work evolves around the following systems...
Operating System: Windows 7 and Windows 8
Server OS: Windows 2008 R2
Data Back-end: Sql Server 2008 R2 and Sql Server 2012
Windows Forms Front-end: Visual Studio 2010 and Visual Studio 2012
Web Based Front-end: Asp.Net 4.0
Smart Mobile Front-end: Android Apps
Over the last 20 odd years that I have been working as a freelancer, it has been my never-ending endeavor to keep up with the latest development versions of the platforms. For me the most important criteria in selecting a technology has been easy availability, wide-spread user-base.