C, C++, Java, Python, Mono (C#)
Cross-platform programming language, is still a little bit far away from me. Recently, I ported Prayer Clock to other programming languages. One of the reasons is to learn more programming languages, another reason is trying to solve the cross-platform problem.
C and C++, my most preferred language(s), with the help of GTK+, can perform well in Windows and Linux. But I didn’t tried on Mac OS X. This is because it needs to be compiled on the OS, rather then cross-compilation. That is why, I ported it to Java before. Though Java claims be WORA (write once run anywhere), yet running in different OS might produce “some” problems, such as minimize to system tray in Linux. And, running on Mac OS X also does not minimize to the system tray as expected.