3. The launcher
The launcher is definitely a killer feature. The launcher, present at the left of the screen,provides a replacement for the standard window lists for managing running apps as well as opening new windows. Moving the mouse over the Ubuntu button or by hovering the mouse near the left edge of the screen reveals the launcher. New applications can be added by simply dragging them from the dash onto the launcher.
The launcher icons get stacked when there is lack of space
A cool feature of the launcher is that when you drag a file onto the launcher, only the applications which can open the file are highlighted.
Dragging a file to the launcher only highlights the application which can open the file
You can open a new window for a particular app by middle clicking on its icon. To view all the windows of an application, click on the application icon.
Two Abiword windows were open here. Clicking on the Abiword icon showed the two windows side by side
The launcher also supports keyboard shortcuts. When you hold the super key (Windows key) for some time, numbers appear on the launcher icons (and letters appear on the lenses). Simply pressing the desired number/letter opens the application.
After pressing the super key for some time, numbers appear on the icons.
If any application needs you attention, its icon shivers and a blue triangle appears at the corner of the Ubuntu button.
The blue triangle at the top left indicates that an application needs your attention
You can even tweak the launcher behavior by using the Unity plugin for Compiz. Icon size, launcher behavior as well as some experimental features can be tweaked from the CompizConfig Settings Manager. Lenses are another cool feature in unity. Lenses are easy ways to access information from particular sources (for example, a YouTube lens would allow the user to search YouTube videos right from Ubuntu). Right now Ubuntu has the applications and the places lens by default, but there are other lenses in development. See here:http://www.omgubuntu.co.uk/2011/04/five-neat-unity-lenses-in-development/
The Ubuntu applications lens
An Ubuntu launcher API is also in development. According to the Ubuntu wiki, the launcher is able to support quicklists, counters and progress bars.
Chromium is just one of many applications which takes advantage of the advanced launcher features.