Tiger's firewall: new and improved
I'm starting to feel like the Cassandra whenever I talk about Mac security. I will grant you that OS X is very secure out of the box, and 10.4.3 has only improved that situation by buffing up the built in firewall, as the Macdevcenter discusses.
You can now collect your firewall rules into sets, and you can disable the firewall temporarily without having to shut it down completely. These new features are only available via the Terminal, so if the thought of typing in commands makes you break out in a cold sweat this isn't for you.
Update: They added a note to the article which mentions that these improvments aren't introduced in 10.4.3, but rather in 10.4. Either way, the firewall is better. Thanks to Mark for pointing that out.