I use this to scrape the current http://xkcd.com/ comic and invert the image and set the background to transparent. Then another geeklet randomly displays the collected images.
You will need the command line tools from ImageMagik http://www.imagemagick.org/ in order to do the image manipulations in in the script.
The script below can be copied into a text file and saved as image.sh somewhere. I use ~/Pictures/XKCD to hold both the images and the script (largely so I can find it later).
#!/bin/sh cd ~/Pictures/XKCD curl -s --location http://xkcd.com/ | grep embedding | sed 's/Image URL (for hotlinking\/embedding): \(.*\)/\1/w temp' TEMP=$(cat temp) rm temp /opt/local/bin/mogrify -type Grayscale +negate -transparent black "$TEMP"
This started out pulling the image from http://dynamic.xkcd.com/random/comic/ but changed to reduce traffic. To switch back, you can replace the link in the script with the dynamic one.