Since I'm working on Web Apps Scanner, I made scripts to automate some vulnerability detection. This work would have been a pain without Beautiful Soup.

This library is simply amazing, here is an example to retrieve every links on a webpage:

import urllib
from BeautifulSoup import BeautifulSoup
htmlContent = urllib.urlopen("http://rgaucher.info/").read()
soup = BeautifulSoup(htmlContent)
for a in soup.fetch('a'):
	print a['href']|php:import urllib

And because it does only html/xml parsing, it's quite easy to deal with cookies, proxies etc. (cookielib & urllib)!