Hardy has Compiz Fusion built in, and comes with some preloaded options. By using synaptic to install the "compizconfig-settings-manager" gets you a ton of control over your desktop eye candy.
But to get the ultimate in Ubuntu desktop effects, you need to use the Emerald Theme Manager. Emerald is also a windows decorator - meaning it controls the appearance of your windows. So with compizconfig-settings-manager, to control things like your wobbly windows, and Emerald to control the way your windows look, you have the best possible control over your Ubuntu desktop. Also there are insane amounts of Emerald themes, and other cool stuff, at gnome-look.org. Here is the easiest way to get Compiz working with Emerald (Thanks hactivision):
First - using synaptic, install Emerald - it lives in the universe repo.
Second - using the applications menu, add / remove programs. search for and install the compiz fusion icon.
once installed, you can find it under applications, system tools menu. The icon will then show up in the panel at the upper right. You can have it start automatically by creating an entry for "fusion-icon --no-start" in start up programs (system menu, preferences, sessions, startup programs tab).
Right Clicking on the icon gives you the following options:
Settings manger (which is the same as the compiz setting manager or advanced desktop effects from the system preferences menu)
Emerald theme manager - this is where you manage your emerald themes - you can download the themes from gnomelook.org, or install this package to get a few loaded automatically for you.
You can also select your windows manager (changing to metacity will turn off almost all eye candy), and you windows decorator. The windows decorator is where you go to enable Emerald. Once you select Emerald as your windows decorator, your windows borders may disappear for a couple of seconds, but they should come back. And then you will be rockin' the emerald.