how about 45 bytes...
http://www.muppetlabs.com/~breadbox/software/tiny/teensy.htm...
How about 31 bytes?
http://www.returninfinity.com/baremetal-helloworld.html
Why use ELF or Linux? Flat binaries (and a custom OS) to the rescue! :)
Why limit yourself to an OS? Design your own instruction set, with a single-bit 'hw' instruction!
As with all games (even Nomic) a game is only a game if there are rules that limit what one can do.
The esoteric language HQ9+ does this.
Indeed, except that one doesn't print "Hello world". :)
Oh, right, you got me, I totally didn't remember that, only the fact, that it was really small and I dug the fact that he put it inside the header.
Many years ago I used to have a 58-byte version, but around the time that x86-64 was being developed, Linux started examining (and thus validating) a couple more fields in the ELF header. It's really a shame, because the corner-cutting in the 62-byte version isn't nearly as impressive (in my own opinion).
http://www.muppetlabs.com/~breadbox/software/tiny/
(62-byte hello world among other things)