If LibreOffice starts too slowly or Acrobat Reader gets stuck in its start sequence yet again, then Gloobus Preview [1] can help if you just want to take a quick peek at a file. The program is a clone of Quick Look [2], the popular Mac OS X tool. It provides a preview of selected files via a simple keyboard shortcut.

Sushi [3] for Gnome 3.2 (gnome-sushi ) is a similar tool. It's based on Java and GtkClutter. Gloobus Preview is written in C++ and uses Gtk+.

Gloobus Preview delivers a high-quality preview for many file types without having to open one of the applications based on the MIME type. You can just select the file while pressing the Super key (the Windows key or Mac Command key on most keyboards)+Spacebar (in the case of Gloobus Preview) or the Spacebar (in the case of Sushi). Both programs display an image of the file's content.

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