How do I make OS X say something when it finds the word "burning" in Console?
Use the following command:

syslog -w|while read l;do [[ $l = *'burning'* ]]&amp;&amp;say the bush is on fire but was not consumed by the flames;done


syslog -w is a shorter alternative to tail -f /var/log/system.log. If you need another log use tail -f /path/to/logfile instead.