Rubbernet!

A firewall protects your computer against unwanted guests from the Internet. But who protects your private data from being sent out? Little Snitch does!

ZoneAlarm Free Firewall blocks hackers from infiltrating your home PC by hiding your computer from unsolicited network traffic. By detecting and preventing intrusions, ZoneAlarm Free Firewall keeps your PC free from viruses that slow down performance, and spyware that steals your personal information, passwords, and financial data.

Hands Off! is an application to monitor and control the access of applications to your network and disks. Being able to monitor the normally unnoticeable activities enables you to make informed decisions regarding the transfer of your private information, hence avoiding confidential information leakage.

IceFloor is the first OS X free graphic frontend for PF. Configure the PF firewall in a few clicks using a very simple interface and a step by step in-app configuration guide (Quick Start).

Radio Silence lets you block individual apps from accessing the internet. It never throws pop-ups on the screen, and is completely invisible.

See connections in real-time: When an app makes a network connection, you see it instantly on your screen. There's no delay and you don't have to use a separate recording mode.

As Apple's built-in Firewall preferences improves in both functionality and security, I will be aiming Flying Buttress more at users who need the advanced firewall configuration, logging, and IP sharing options found in Flying Buttress.