Also the related Beryl which was more commonly used before the projects merged(?).
https://trends.google.com/trends/explore?date=all&geo=US&q=C...
https://trends.google.com/trends/explore?date=all&geo=US&q=C...
Then Compiz Fusion came along (which was supposed to be all of Beryl's updates being merged into Compiz), but they dropped like 2/3rds of the effects and it became a pain to make functional at all. That was when I stopped using it.