Ubuntu 12.04
overview
The default configuration option installed as standard is User Interface.
There are three further unity configuration options used in this answer that can be installed:
Note: In previous answers, the utility CCSM was extensively used as the primary configuration tool. The use of this tool is strongly not recommended and can break your desktop. In this answer, CCSM is only used where the other tools do not offer the configuration options discussed.
Note that some changes only appear after logging out and in again (i.e. restarting X).
User Interface
- Hit the Dash and search for appearance

From the Appearance tab you can configure the:
- wallpaper
- theme
- size of the launcher icons

From the Behaviour tab you can configure the:
- how to invoke the launcher by moving the mouse (hot-spot) - either left-side of the screen or the top-left corner
- how quickly the launcher is revealed - lower the slide bar, the longer the mouse needs to be at the hot-spot to be revealed.
MyUnity
- Hit Alt+F2 and type
myunity and hit enter.
You can now configure quite a few different settings, like the launcher behavior, dash configuration, panel transparency, desktop icons and various font settings.
Launcher

- color - Launcher background color
- size - Launcher icon size
- Transparency - Background transparency of the launcher
- Show devices - Show removable USB drives as an icon
Behavior - How the launcher interacts with windows
- Fixed - The launcher will never hide.
- Hidden - The launcher will hide when a window would overlay it.
Display - What effect the launcher should use when hiding i.e. to fade away or to slide (or both)
Backlights - Style of icon background
- Icons On - the icon back light will always be on.

- Active Icons On - the icon back light will be on as long as the application is running.

- Icons Off - No backlights on icons

- Only Icons Edge - the edge illumination will be on as long as the application is running.

Launcher Quicklists

This option allows you to create quicklists - quicklists are a submenu that are displayed when you right-click a launcher icon.
For example - shutter

Dash

- Display available apps - control whether similar applications from the software center should be displayed
- Display recent apps - control whether applications you have recently used should be displayed
Blur - how or if Dash background is displayed - default is to blur the background
- Off - No Blur
- Smart - Active Blur - This means it actively blurs what is behind it.
- On - snapshot of the desktop that doesn't get updated (in cases where the drivers can't handle it)
Dash Size - whether the dash shows in netbook or desktop style depending on the screen resolution
Panel

- Transparency - how transparent the top-panel should be displayed
- Transparency Maximized Toggle - if you are using a transparent top-panel this toggle controls whether an application that is maximised has its decoration also displayed transparently or in the theme colour.
Desktop

- This tab determines whether the icons shown in the image appears on the desktop
- Window animation - whether the launch and minimize window effect is displayed or not
- v desktop & h desktop - controls the number of vertical and horizontal workspaces (default 2x2)
Fonts

- Font antialiasing - how smooth the fonts are displayed
- Font hinting - adjust the display of the outline font
- System/Document/Desktop/Window Title/Monospace - change the font for the desktop type
Themes

Any themes that you have installed or manually installed (/usr/share/themes or ~/.themes) together with manually installed icons (/usr/share/icons or ~/.icons) can be chosen.
Configuration Editor (dconf-editor)
Where an option is not described, then this functionality can be achieved through MyUnity described above.
Open up the Configuration Editor by pressing Alt + F2 and typing dconf-editor
Navigate to Desktop -> Unity to find the options below:
home-expanded - Whether the home screen of the Dash should be expanded (Expanded) or not (Not Expanded).
sub-key Dash - home-lens-ordering - List of lens ids specifying how lenses should be ordered in the Dash home screen.
- sub-key Devices -
favorites - List of device uuid for favorites on the launcher.
- sub-key Launcher -
favorites - list of icons (their .desktop names) shown by default on the launcher
- sub-key Panel -
systray-whitelist - List of client names, resource classes or wm classes to allow in the Panel's systray implementation. A value of [All] will allow any system-tray based application that is not by default a indicator to be displayed
CompizConfig Settings Manager
- Hit Alt+F2 and type
ccsm and hit enter.
Where an option is not described, then this functionality can be achieved through MyUnity described above.
On the Behaviour tab you can configure:
1. The key to invoke the HUD - Head Up Display - by default this is the Alt key.
The key to show the launcher which by default is the Super key. This will also affect the key used to show the dash (if tapped) and the shortcuts shown when keeping Super pressed.
The key to put keyboard-focus on the launcher so you can navigate using your keyboard (default Alt + F1).
The key to open a Search Command dash where you can enter a command name you want to execute. (dafault Alt + F2).
The key to open the first panel menu (default F10).
The key to define the Application switcher (default Super+Tab
The key to define the Reverse the Application switcher (default Shift+Super+Tab
On the Switcher Tab:

Automatically grid windows on timer in switcher: Turn this off if you want don't want to automatically expand multiple windows in alt-tab.
Bias alt-tab sorting to prefer windows on the current viewport: Select this if you want alt tab to prioritize the order in which applications are shows in alt-tab. Applications in your current workspace are listed first.
Show minimized windows in switcher: Turn this off if you don't want minimized windows appearing in the switcher
On the Experimental tab (might change hence the name):


The Launch Animation sets how the icons are animated.
- None - no animation will be shown.
- Pulse Until Running - the icon's back light will pulse till it loads up.
- Blink - the icon's back light will blink.
The Urgent Animation sets how an icon will inform you of something important.
- None - no animation.
- Pulse - it will pulse.
- Wiggle - it will wiggle.
Launcher Reveal Pressure - amount of mouse pressure required to reveal the launcher when the mouse is located at the launcher hot-spot
Launcher Edge Stop Overcome Pressure - amount of mouse pressure required to push into the next monitor
Pressure Decay Rate - the rate at which the mouse pressure decays
Edge Stop Velocity - the maximum velocity at which the mouse will still be stopped
- Fade on bfb and Slide - fades based on the position of your cursor in the bfb (big funny button - the one in the top left of your launcher with the Ubuntu circle of friends on it) and slides.
- Slide only - it will only slide.
- Fade only - it will only fade.
- Fade and Slide - it will fade and slide.
The Automaximize value sets the minimum value to trigger automaximize.
Enable Shortcut Hints Overlay - pressing and holding the Super key displays the keyboard shortcuts overlay. This can be disabled through this setting.
Menus Fade-in duration - duration (in milliseconds) that the global menu fade-in animation takes to display when the mouse moves into the global menu region.
Menus Fade-out duration - duration (in milliseconds) that the global menu fade-out animation to display when the mouse moves into the global menu region.
Menus discovery duration - number of seconds the global menu should display when an application is first started
Menus discovery fade-in duration - duration (in milliseconds) that the fade-in animation takes when the global menu is displayed for an launched application
Menus discovery fade-out duration - duration (in milliseconds) that the fade-out animation takes when the global menu is displayed for an launched application