Basic hash creation methods for a given dictionary.

hasher.rb

#Hash function which converts hash_me("leep", dictionary) => 13427273
def hash_me(text, dictionary)
  h = 7
  dictionary = "acdegilmnoprstuw"

  text.size.times do |i|
    h = (h * 37) + dictionary.index(text[i]).to_i
  end

  h
end

def find_position(number, dictionary)
  dictionary.split("").each_with_index do |l, i|
    div, mod = (number - i).divmod(37)
    if mod == 0
      return div, l
      break
    end
  end
  ["", 0]
end

#Unhash function which converts unhash_me(13427273, dictionary) => "leep
def unhash_me(number, dictionary)
  h = 7
  text = ""
  while number > h
    number, letter = find_position(number, dictionary)
    text << letter
  end

  text.reverse
end

#Usage: set the dictionary and the number to be decoded
dictionary = "acdegilmnoprstuw"
number  = 910897038977002

#Call the unhash fuction
text = unhash_me(number, dictionary)

#Print the victory mark if everything went ok.
puts "Sucess!!" if number == hash_me(text, dictionary)

I Like your solution, and I've translated to Java as a fork (here https://gist.github.com/MuhammadHewedy/11380342)