Monitoring for link spam in blogs can be done by using pavuk. Just spider the site periodically and look for new links:

cd $HOME/tmp /usr/bin/pavuk -noRobots -dump_urlfd 2 -dumpfd 1 -adomain $DOMAIN \ http://www.$DOMAIN/blog/ >/dev/null 2> $DOMAIN-urls.log /bin/sort $DOMAIN-urls.log | /bin/uniq > $DOMAIN-urls-new.log /usr/bin/diff $DOMAIN-urls-old.log $DOMAIN-urls-new.log /bin/mv $DOMAIN-urls-new.log $DOMAIN-urls-old.log