Are there any "clean" alternatives to Unicorn for HTTP streaming?

Are there any "clean" alternatives to Unicorn for HTTP streaming?

By "clean" I mean using the :stream option during render.

class MyController < ActionController::Base
  def index
    render :stream => true
  end
end

Unicorn is "clean".

What I should have wrote is "In addition to Unicorn, are there any
other HTTP Servers, for Ruby on Rails, that "cleanly" support HTTP
streaming?"

Thank you!