snippet.rb

def mode(arr=[])
  hsh = arr.inject(Hash.new(1)) { |hash, item| hash[item] += 1; hash }
  max = hsh.values.max
  hsh.inject([]) { |arr, item| arr << item[0] if item[1] >= max; arr}
end

p mode %w(a b a a b c dd e e e) # ["e", "a"]
p mode %w(a b a a b c dd e e) # ["a"]
p mode %w(snowboarding is more than fun. super fun.) # ["fun."]