C program that changes it's proctitle (works on FreeBSD).

sources.c

#include <stdio.h>
#include <unistd.h>  // for sleep()

// Please note, that Linux does not supports setproctitle()
// (but FreeBSD does)

int main (void) {
    setproctitle("I am C program! (%d)", getpid());

    int MyTick=0;

    puts ("Let's get some rest...");

    while (MyTick < 5)
    {
        printf("    %d s left...\n", 5-MyTick);
        sleep(1);
        MyTick++;
    }

    printf("Hello world!\n");

    return 0;
}

Some folks miss this call on Linux: http://stupefydeveloper.blogspot.ru/2008/10/linux-change-process-name.html