TuxGuardian is an application-based firewall that allows the implementation of access control policies in order to identify and control every application that tries to access the network. It works with or without the intervention of the user by means of a simple graphical interface. This means that a machine can be made secure by controlling and forbidding transmission and reception of data by unauthorized applications. It makes use of the latest security mechanisms included in Linux 2.6 such as the LSM framework.
IsinGlass is a firewall setup script designed to protect dial-up users (but also useful for others). It protects your system against security holes in programs the user may not even know they're running. Most users can run it "out of the box" without any configuration required. It will automatically detects network interfaces and IP addresses. Now works with ipchains.
mfw allows multiple firewall configurations to be managed from the commandline on Mac OS X. Multiple firewall modes (and easy means of selecting between them) are useful on laptops, where one may want a default paranoid firewall, a mode for network scanning with nmap, modes for various networked games, or to run a software Network Address Translation (NAT) wireless base station.