Cf. http://someonewhocares.org/hosts/

# Use this [hosts] file to prevent your computer from connecting to selected
# internet hosts. This is an easy and effective way to protect you from
# many types of spyware, reduces bandwidth use, blocks certain pop-up
# traps, prevents user tracking by way of "web bugs" embedded in spam,
# provides partial protection to IE from certain web-based exploits and
# blocks most advertising you would otherwise be subjected to on the
# internet.