This is essentially a fork of the python version of JSMin. It takes a JavaScript file and spits out a bookmarklet-ified version. That is, it runs an aggressive version of JSMin and prepends it with javascript:.
I found myself using jsmin.py and then tweaking the output by hand. By far, the most annoying adjustments were removing the remaining newlines. Those small things really add up if you find yourself developing and testing a JavaScript bookmarklet.