Gnome Do (http://do.davebsd.com/)

GNOME Do allows you to quickly search for many items present in your GNOME desktop environment.  These include applications, Evolution contacts, Firefox bookmarks, files, artists and albums in Rhythmbox, Pidgin buddies, etc.), as well as letting you perform commonly used actions on those items (Run, Open, Email, Chat, Play, etc.). 

Press Super+Spave (Windows+