Bookmarklets I've written or found useful

bookmarklet-generator.js

/*
 * Prompts for the URL of a script, then creates a bookmarklet to load and run the script.
 *
 * javascript:(function(u) {u=prompt('Script URL');u&&prompt('Bookmarklet', 'javascript:(function(d,s){s=d.createElement("script");s.src="'+u.replace(/^https?:/,'')+'?cb="+Math.random();d.body.appendChild(s)})(document)') })()
 */
(function(u) {
  u = prompt('Script URL');
  u && prompt('Bookmarklet', 
    'javascript:(function(d,s){s=d.createElement("script");s.src="' +
    u.replace(/^https?:/,'') +
    '?cb="+Math.random();d.body.appendChild(s)})(document)')
})()

/*
 * Same, but shows a element at the top of the page with a link you can drag to your bookmarks.
 *
 * javascript:(function(d, u, b, a){u=prompt('Script URL');if(u){b='javascript:(function(d,s){s=d.createElement("script");s.src="'+u.replace(/^https?:/,'')+'?cb="+Math.random();d.body.appendChild(s)})(document)';a = d.createElement('a');a.setAttribute('style','display:block;position:fixed;top:10px;width:640px;left:50%;margin-left:-320px;border:solid 2px black;padding:6px;font-weight:bold;background:#fff');a.href = a.textContent = b;d.body.appendChild(a)}})(document)
 */
(function(d, u, b, a) {
  u = prompt('Script URL');
  if (u) {
    b = 'javascript:(function(d,s){s=d.createElement("script");s.src="' +
      u.replace(/^https?:/,'') +
      '?cb="+Math.random();d.body.appendChild(s)})(document)';
    a = d.createElement('a');
    a.setAttribute('style', 'display:block;position:fixed;top:10px;width:640px;left:50%;margin-left:-320px;border:solid 2px black;padding:6px;font-weight:bold;background:#fff');
    a.href = a.textContent = b;
    d.body.appendChild(a)
  }
})(document)