I will have to say Python like so many others, and honestly I couldn't expect less. I know C is a very second close to it and I couldn't agree more; well more or less.
The only reason I'm saying python is because it is something I am most fluent in. The only other being C. Yes, I have done and also still do Java, but only for Android. I have and will do PHP if it needs it, such as anything web and needing a DB, or universal across multiple PC's that needs something in common to refer to such as a DB of tickets or something.
Hell, even GUI based apps and front-ends go to python since haven't been on or with Windows for such a long time, and even if Windows was an option, python minus file paths is my first choice. But python isn't adopted in the working world, but LAMP and WAMP is, P being PHP in my case since python is in the know and here for a lot of corporate America.
Although, when working with le Atmel or anything that doesn't use an OS it will be C. I do, however, use python on embedded linux such as ARM tech. But when and where C doesn't come in, it will be C. I have also done a bit of driver work and stuff with linux and getting a damn game controller to work with out the accelerometer and such, then C is the answer.
Python is coming up for a lot of stuff, mostly because it is so easy. And it can be powerful with the libs avail like hooking into DLLs and such. Anything python doesn't make since with it will be C for me.
I mentioned Java, and it is and only for now for Android Dev. Yes C/++ can be used as a core dev language, but the Devs them selves recommend using Java instead. C/++ with android is meant for things like 3D speed up and system and performance critical things, things I haven't come accross yet with android.
I have done VB.NET in school, and delved in C# and others, but if it can't be done with C or python, then meh.
Notable mention is, PBASIC and BASIC itself. Only used with 8bit microcontrollers though, so I can't tell much other than spinning a servo or reading from COM or flashing an LED.
TL:DR:
Python, C/++, PBASIC (special cases), PHP. In that order pending on application.
I have also been interested in BrainFuck, a lot like LuLzcode or whatever, but I have seen more on HackADay with BrainFuck than Lolcode. Probably will never get around to it, but much rofl's for it.