SevenBits is an open-source loader for many PC and MAC systems that supports the operation of several common distributions such as Fedora, Red Hat, Mandriva, and openSUSE. It is also designed as a Linux-native loader and supports almost all types of Linux, including SUSE, Fedora, Debian and many others. The main feature of SevenBits, however, is its ability to work directly with USB flash drives. It is created by developers that work closely with Novell, the leading Linux vendor. So if you are looking for a way to load Linux onto your MAC (or other Linux based platforms), SevenBits can be your best solution. In addition to working directly with USB drives, it also supports other EFi devices such as printers and cameras.
SevenBits is not only designed for use with Linux, but also with Mac Linux and Windows, although support for these operating systems is not as robust as that available for Linux. However, it is worth trying if you have an interest in Efi. It is free and contains a very simple to use graphical interface, which is very similar to that of the popular Retroame. However, it also supports many other distributions, and works quite well with older MACs running Unix. It has been developed by several companies over the years, who continue to add new features and fixes to the software every few months.