This is an old page. My new program The Polynomial includes all the functionality of Attractor Viewer, and lot more (realtime preview of your modifications, load and save, Linux and OS X native binaries, etc).
Download:
Binary for windows (version 2009-01-18-2)
System requirements:
If it does not work, install latest drivers(!). In particular, old ATI drivers have a bug in implementation of framebuffer objects.
Screenshots:
(click on image to open full sized version)