Source: How to be a modern… by Jeffrey Leek [Leanpub PDF/iPad/Kindle]
This book looks very useful for PhD students and also to some extent for more experienced researchers willing to get up-to-speed with the use of modern communication tools and on-line media and forums.
It covers a lot of subjects concisely and is very up-to-date. It is an easy read but full of useful information and ideas.
The e-book has a suggested price, but you can chose to get it for free or pay less if you are on a tight budget. Payment is fully voluntary, so you can also pay more than the suggested price if you want to support the author.