Although I generally favor open-source technologies for economic, technological and personal reasons, I believe that every problem has its own optimal solution. I firmly believe that the "one size fits all" does not apply to software development.
Here's the list of tools that I employ for the majority of my work:
Languages
- Ruby
- PHP
- Javascript
- C/C++/Objective-C
Markups
- HTML/DHTML/XHTML
- XML
Databases
- MySQL
- PostgresSQL
Frameworks
- Rails
- Cocoa
Operating Systems
- Mac OS X
- Linux and many flavors of UNIX
- Windows
Integration
I also use some third party librairies, frameworks and tools that are simply too numerous to detail here. I am flexible and can adapt to your preferences.
Should you wonder, I own a Mac, a Windows PC and a Linux Server and am disposed to work on either platforms.