This post is about the application finder.
You can press Arrow Down to expand the Application Finder and show application categories installed on the system.
If you type something it will show the matching program in the left side. If you press Arrow Down then the cursor will switch to the column of matching application, pressing Enter will launch the selected app.
You can also press Alt - F3 and the Application Finder will open in expanded mode.
There is a number of custom actions defined out of the box.
#command will open a terminal and show the man page for command.
!command will open a terminal and run command, the terminal will close when the command is executed.
!w some text will open the default web browser and search on Wikipedia for some text
http://google.com will open the URL in the default web browser.
If you press Preferences and the Custom Actions tab, you can add your own actions.