Use only after consulting your conscience.

letterpress.py

#!/bin/env python2.7
#-*- coding:UTF-8 -*-
import sys
import collections

letters = collections.Counter(list(''.join(sys.argv[1:])))

words = [word.strip() for word in open('/usr/share/dict/words').readlines()
        if word.find("'") == -1]

def matches(word, letters):
    return (len(collections.Counter(word) - letters) == 0)

possible = [word for word in words if matches(word, letters)]

print letters
print list(reversed(sorted(sorted(possible), key=len)))