Simple and easy way to search for books using Ubuntu Unity Dash through many books search engines ex.Google Books, and online books libraries, such as Calibre database. Select the book and it will open web page to read the book on the default web browser. Also you can use it to search through your available books on ~/Documents directory for currently active user.
Install Books Lens On Ubuntu 11.10 Oneiric Ocelot and Ubuntu 11.04 Natty Narwhal using PPA
sudo add-apt-repository ppa:davidc3/books-lens
sudo apt-get update
sudo apt-get install unity-lens-books "Ubuntu 11.10 Oneiric"
sudo apt-get install unity-books-lens "Ubuntu 11.04 Natty"
Unity Lens “Books Lens” source.