jjrakman

Here's some more that I don't see listed here:

http://sketchup.google.com/

http://www.sausage.com/reptile-free.html

http://digilander.libero.it/giulios/Eng/Index.htm

http://www.jahshaka.org/

http://www.planetside.co.uk/terragen/

http://www.apophysis.org/

http://www.detonationfilms.com/missionstatement.htm

http://www.cs.utexas.edu/~okan/Pixie/pixie.htm

http://www.thebest3d.com/dogwaffle/free/