C

“It’s in C and is low-level enough to stay out of your way — but still manages to abstract the graphics context, windows, events.”

“Since the project I work on is a command-line tool that is primarily implemented in C, I use the usual CLI development tools, e.g.”

“If that's not hip enough for you already, I actually type in a Dvorak variant that a friend of mine came up with, a compromise between Dvorak's letter placement and QWERTY's punctuation placement, which is better for programming in C-like languages.”

“I'll also use C if I need it for performance optimizations.”

“I've also been known to use the C preprocessor to do silly things like generate printer art postscript files.”