Ok so I just discovered Beryl and it rocks!
Beryl is a fork of Compiz with very much the same features and some more. You have probably already seen the screenshots on various Linux forums.
I never tried Compiz since many people reported it a mission to get going in KDE and I absolutely hate Gnome, so I never tried it. Beryl on the other hand is very easy to install and it works superbly with KDE!
Read through the Wiki, install it and enjoy the wobbly windows, rain on the desktop and whatnot!
There is much more options to exploit, I just quickly took these few screenshots to wet the appetite.
Quickly now, install it and enjoy the eye-candy!