Free for this month (May, 2012) is an e-Book version of Carl Zimmer’s popular science book, A Planet of Viruses.
To get your copy, go to the University of Chicago Press website for the book and enter your email address in the space provided. You will be sent an email with a link from which you can download a copy. The book is displayed using Adobe’s Digital Editions software, of which I have little experience (but see first Footnote).
Carl Zimmer is a long-time science writer and author of several books including The Tangled Bank, (evolution), Parasite Rex (parasites), Science Ink (a collection of tattoos with scientific themes and their stories), Brain Cuttings, More Brain Cuttings (the working of the mind) among others.
Footnotes
I hope to have this blog back into more regular activity next week.

An interesting read. Shame it’s not referenced. What do you make of this passage?
“Scientists have gathered a great deal of evidence that children who get sick with relatively harmless viruses and bacteria may be protected from immune disorders when they get older, such as allergies and Crohn disease. Human rhinoviruses may help train our immune systems not to overreact to minor triggers, instead directing their assaults to real threats. Perhaps we should not think of colds as ancient enemies but as wise old tutors.”