Gloobus-Preview is an extension for the Gnome Desktop Environment designed to enable a full screen preview of any kind of file. It’s based on Apple’s “Quicklook”. GNOME 3.2 have its own quick file previewer called gnome-sushi. You can install it by typing "sudo apt-get install gnome-sushi". But if you want to use Gloobus Preview instead because it supports more file types, you can install it on Ubuntu 11.10 Oneiric Ocelot easily.

Just type the following command to install Gloobus Preview on Ubuntu 11.10 Oneiric Ocelot:
  • sudo add-apt-repository ppa:gloobus-dev/gloobus-preview
  • sudo apt-get update
  • sudo apt-get install gloobus-preview gloobus-sushi libgdk-pixbuf2.0-dev

Usage instruction
Simply select your file in Nautilus file browser and hit "Space" on keyboard to do a quick preview of the file.