Common Lisp has unless too, I use it where it makes sense.
In Perl you can write postfix conditionals: `thing() unless $condition`, which at least is more natural usage of "unless" to a native English speaker than the other way around. That's the best way to use it IMO.
It's the same in Ruby. It's even mentioned in TFA.
Those who don't know history are doomed to repeat it. ;-)