Trolltech - http://www.trolltech.com - If you write programs in C++ and distribute you programs for free, you can download and use there "cross-platform C++ GUI application development framework with graphical user interface designer" (IDE for short) for no charge.  By using Qt, you develop and maintain a single source code base that runs with native performance on all major desktop operating systems, including but not limited to Microsoft Windows 95/98/2000, Microsoft Windows NT, MacOS X, Linux, Solaris, HP-UX, Tru64 (Digital UNIX), Irix, FreeBSD, BSD/OS, SCO and AIX.