If you are an Ubuntu user and a fan of the new Unity interface, you might be interested in a new lens in development by David Callé. The Books Lens provides a real-time search interface for e-books. It currently interfaces with Google Books, Project Gutenberg and Forgotten Books. By the time you read this, that list probably will have grown.
The Books Lens instantly finds metadata on your search, including book covers, and gives you direct links to the books themselves. For us book nerds, it's quite a handy little tool. Check it out yourself at https://launchpad.net/unity-books-lens, or install the PPA with:
sudo apt-add-repository ppa:davidc3/books-lens
Then, install the package unity-books-lens.
This screenshot, from the project page, shows the search results for "Dora".