End users should take reasonable precautions in revealing their email addresses.
End users can use automated filtering on their own computers.
System administrators can use appropriate tools to keep spam off of their systems.
Perhaps the best way to avoid spam is to avoid giving your email address to spammers, directly or indirectly. Basic computer literacy should include an understanding of the basics of spamming and spam avoidance. One should never reply to a spam email, or click an "opt-out" link (this simply confirms that an email address is "live").
MailMask.net allows you to give out an alias e-mail address on websites and newsgroups. This alias address will prevent you from ever getting spam in your normal mailbox!