This is an indicator for the Ubuntu dashboard. It could be considered the Mac OS X alternative to Spotlight.
Synapse Indicator
Synapse Indicator is a indicator for panel elementary OS which uses Synapse to launch applications and search for files on the system using Zeitgeist. Although the indicator was created for elementary OS, it can be used without any problem in its mother distribution, Ubuntu.
Use
The use of Indicator Synapse is exactly the same as Synapse, although in this case you have to click on the icon of the panel to be able to write the search term and immediately afterwards the results will appear organized by categories (applications, files, Google search, WolframAlpha search…). The appearance of Indicator Synapse is very similar to that of Spotlight for Mac OS X.
Installation
Install Indicator Synapse on elementary OS Moon o Ubuntu 13.04, 12.10 y 12.04 It is a very simple task thanks to the PPA that appears below these lines, although, yes, it must be borne in mind that it is a first version with many things still to be polished.
The only thing to do then to perform the installation is to add the following repository:
sudo add-apt-repository ppa:gotwig/weekly
Then we simply refresh the information and install the necessary package:
sudo apt-get update && sudo apt-get install indicator-synapse
In order for the indicator to take effect, you have to restart the panel, or close and log in with a new account.
More information - Indicator Brightness, indicator to change the brightness of the screen in Ubuntu in a simple way
Source - Website Upd8