You could rank H!P members indirectly by comparing them to wild animals, or things that you find under sofa cushions, or kinds of school cafeteria food, and then everybody could vote on the comparison items (assigning them positive or negative numbers).
For example, if someone were to say that Nakky was 35% better than a lint-covered half of a Tootsie Roll, and we voted to assign a value of -15 to lint-covered Tootsie Roll halves, then 100% - 35% = 65%, so Nakky would get 65% of -15 = -9.75 points.
That's pretty simple, isn't it?