Based on the Javascript Crunchinator Demo, you can use this to quickly create a bookmarklet from some javascript code.
Enter your javascript code in the text area below Input. Enter a name for the bookmarklet in the Name field. Click crunch, and the code will be compressed, and turned into a link under output. You can then drag this to your bookmarks toolbar as a bookmarklet, or right click and bookmark it, or just click it to try it out.
Note that your code will automatically be wrapped in a function to make it bookmarklet-friendly.