If you are a geek that uses Tomboy to write notes, you will like Unity Tomboy Lens for sure.
Unity Tomboy Lens allows you to preview your note content by right clicking the note in Dash. You can also search and open notes in the Unity Dash and get the notes in your Tomboy Lens or in the home lens.
Despite the name, Unity Tomboy Lens also integrates well with Gnome.
How to Install Unity Tomboy Lens on Ubuntu 13.04 Raring Ringtail, Ubuntu 12.10 Quantal Quetzal and Ubuntu 12.04 Precise Pangolin:
$ sudo add-apt-repository ppa:remi.rerolle/unity-lens-tomboy
$ sudo apt-get update
$ sudo apt-get install unity-lens-tomboy
Just log back in and you will find the new lens in Dash.