Although I have downloaded compiz, ccsm, compiz-plugins, compiz-fusion-plugins-main and compiz-fusion-plugins-extra, I still cannot find how to activate the famous Atlantis effect. In the "Effects" category, I can choose the gears in the cube but not the aquarium. I really would have liked to see fishes swimming around in my desktop.
SnapOverflow
You have to compile compiz-plugins-unsupported from the repos.
Instructions can be found here. You can download the files you need to compile here: http://releases.compiz-fusion.org/0.8.6/
Ensure that you install compiz* dev packages first, and that you have build-essential installed as well.
See this site for just about everything you need on compiz =)