Well, any lang that is 'Turing complete' (?) is a real prog lang (logically they are all equiv to each other ie capable).
Some langs are better suited to certain applications than others.
A lang such as one of the Unix shells that is strictly an interpreted lang will be significantly slower than a 'compiled' eg C, Perl, Java.
Obviously, HTML is not a 'Turing complete' lang.
There's no formal distinction between scripting and programming, unless you only use interpreted langs for the former and compiled ones for the latter.

C is winning of course. I am guessing everyone who voted for C has K&R on their desk. I do.

I always laugh about a guy at my work, lives and dies by Ruby.

I threw out my old K&R stuff and just have the ANSI C stuff sitting on the desk now. :)

Ruby *does* have some neat features. Haven't found a practical use for standalone apps though. RoR is pretty cool in regards to how little code that needs to be written to implement powerful functionality. However, the MVC model (IMO) makes debugging difficult compared to C...

My heart goes to C, but rather GNU flavor of it. There are few neat additions compare to K&R.

Given choices at the title, I'd split second place between Python and Java.

My criteria for programming language usefulness is the thickness of more or less full description of them, using this qualifier I'd put:
1. C - K&R is really thin
2. Java & Python - O'Reilly books are thin enough
3. C++ - distant last, Stroustrup's volume is huge

ZFS is already FOSS, although not GPL outside grub ZFS file loader.

The strangest language i have ever seen is Piet!

http://www.dangermouse.net/esoteric/piet.html

Use the language that is best suited for the project.
c for low level systems coding
perl for text rocessing
c++ / objective-c for gui work.
[ objective-c is the foundation of OSX Cocoa framework, so it is a usefull language to know ]

Fortran for anything using massive mathematics, like autocad needs for stress testing designs.
COBOL, great for reports.

And Object Oriented COBOL is great for ... nothing really. Its plain predecessor still exist only because there is much software around written using this venerable artifact.

if it cant be done in LOGO then you dont need to do it ;-)