Flam3 is described as 'Flames are algorithmically generated images and animations. The software was originally written in 1992 and released as open source, aka free software. Over the years it has been greatly expanded, and is now widely used to create art and special effects'. There are four alternatives to Flam3 for Windows, Linux and Mac. The best alternative is Electric Sheep, which is both free and Open Source. Other great apps like Flam3 are Apophysis (Free, Open Source), Qosmic (Free, Open Source) and Oxidizer (Free, Open Source).
Apophysis is a fractal flame editor and renderer for Microsoft Windows. It was created by Mark Townsend by translating Scott Draves original C code into Delphi and adding a graphical user interface.
Qosmic is graphical interface for creating, editing, and rendering flam3 fractal images. The electricsheep screen saver has been gaining popularity, and Qosmic was developed to provide a Qt interface for people interested in creating and contributing sheep.