This tool is based on images posted by user ZrX over on the Kryoflux.org forums. It's not nearly as in-depth as his tool, but I thought it would make a good starting point for doing some html5 canvas work.
USAGE: Select a color map (Default is green) and drag a d64 image from your hard drive to the 1541 drive in the upper left and watch the magic. Click the Download button to save the png image to your computer (Not currently working in IE).
Note: Track 18 (the directory) will always show up as an aqua-ish color.