Greasemonkey script that generates and auto fills passwords using the website's domain as the seed. http://idioticdev.com/sprouted-passwords.html

sprouted-passwords.user.js

// ==UserScript==
// @name        Sprouted Passwords
// @namespace   http://idioticdev.com
// @description Generate and autofill passwords using that website's domain as the seed.
// @include     *
// @version     1.3
// @require     http://cdnjs.cloudflare.com/ajax/libs/jquery/3.0.0/jquery.min.js
// @require     http://cdnjs.cloudflare.com/ajax/libs/seedrandom/2.4.2/seedrandom.min.js
// @grant       GM_registerMenuCommand
// ==/UserScript==
const length = 26
const salt   = 'Your Salt'

const hostname = window.location.hostname.replace('www.', '')

function sprout (seed = hostname) {
  let salted = seed + salt
  let rand = new Math.seedrandom(salted)
  let value = ''
  for (let i = 0; i < length; i++) {
    value += String.fromCharCode(rand() * 94 + 33)
  }

  return value
}

$("input[type='password']").val(sprout())
GM_registerMenuCommand("Show password", () => prompt(hostname, sprout()))
GM_registerMenuCommand("From seed ...", () => {
  let seed = prompt("What seed?", hostname)
  prompt (seed, sprout(seed))
})
GM_registerMenuCommand("Fill from seed ...", () => {
  let seed = prompt("What seed?", hostname)
  $("input[type='password']").val(sprout(seed))
})

I like the salt