Search Files / Application on Ubuntu using - Synapse

If you ever used Gnome Do / Quicksilver / Gnome Launch Box, you'll feel right at home with Synapse, if not, the only thing you need to do is run Synapse (or press Ctrl+Space to summon it), type what you're looking for, and Synapse will present you a list of items that match your query. Once you found the item you were looking for, you can perform an action on it (and these are defined by the plugins you're using). If you don't like the default action, just press Tab and search appropriate action.

The default set of plugins shipped with Synapse are as follows: -
  * Applications – searches your desktop files
  * Banshee – allows you to play/enqueue music files in Banshee
  * Commands – runs any command (ie. “sudo apt-get update”)
  * Devhelp – search documentation using Devhelp
  * Dictionary – find definitions of words
  * Directory search – allows opening of commonly used directories
  * Gnome session – log out, shut down, restart
  * Hybrid search – complete Zeitgeist results by searching for similar files
  * Rhytmbox – play/enqueue music files in Rhythmbox
  * UPower – suspend & hibernate your computer
  * Zeitgeist – search anything logged by Zeitgeist

Install Synapse in Ubuntu:
Open up the terminal and type following commands to install Synapse

sudo apt-add-ppa repository: synapse-core/ppa
sudo apt-get update
sudo apt-get install synapse

After successful installation you can start Synapse from Applications > Accessories. Once the application is running, summon it using the CTRL + SPACE keys (this can be changed in the Synapse settings).

One of the things that first stands out is how quickly Synapse reacts to any search. It will find any match for applications, Actions, Images, Documents, Audio, Video, etc., even if the term entered does not match a complete word, but separate letters.