OS X Terminal: Log All Commands into the system.log
Pasting the follow code into ~/.bash_profile will append any commands entered into the syslog with the tag BASHFU.
PROMPT_COMMAND='history -a;tail -n1 ~/.sh_history | logger -t BASHFU'
This is a fun trick that I use with my Single-user Mode Intrusion Detection System. Some other uses I would like to try this for is to log only sudo commands by all users.