Speaking xkcd... this script will fetch a random cartoon for you (great in the morning with a cup of coffee)
Code:
#!/bin/sh
wget -q http://dynamic.xkcd.com/comic/random/ -O - | \
grep 'hotlinking/embedding' | cut -d: -f 2-3 | \
wget -q -i - -O /tmp/xkcd.jpg
# your-image-viewer-here /tmp/xkcd.jpg