boomlet is a bookmarklet compiler that encloses, encodes, minifies your Javascript file and automatically opens an HTML page with your new bookmarklet for immediate use. Made for NodeJS, it's available via NPM and open sourced on GitHub.
Rather than copying and pasting your JavaScript into a webpage, like this one, boomlet allows you to speed up your dev, deploy and testing iterations. I personally use Sublime Text and a Makefile for building bookmarklets. See the GitHub repo for more info.
You can use this web page to generate a bookmarklet without needing NodeJS or the boomlet module. (get the gist 7767192)