Use the following command in your shell to generate unique passwords for websites based on a master password. md5 generates a hash of the text string 'SECRET:domain.tld'. awk and cut retrieve first 10 characters of said hash. 'SECRET' would be your master password. 'domain.tld' would be the site in question (eg, textsnippets.com).
/sbin/md5 -s 'SECRET:domain.tld' | awk '{print $4}' | cut -c 1-10