30 6 * * * /usr/bin/wget -O /backup/web_services/delicious/delicious
30 6 * * * /usr/bin/wget -O /backup/web_services/lj/lj_`date +\%F`.xml http://www.livejournal.com/users/<USER
This requires that your put your login information in .netrc (reminder - chmod 600). See man netrc for more info on that. Obviously, the directories you're backing up into must also exist.
This is particularly timely given the recent outages that del.icio.us has had.