I would love to share a site that was recommended to me by Amanda Craven. This site, MakeUseOf, is a  sheer treasure chest of great resources that cover a vast range of relevant internet marketing subjects.

The site is called MakeUseOf and one of their best sections is dedicated to an astonishing array of downloadable guides covering everything from 'Learn LinkedIn' and 'Your Guide To Social Media Marketing' to 'An Idiot's Guide To Photoshop.'  

You get to download them by either subscribing to their newsletter (well worth it) or sharing the page on Twitter or Facebook.  In my opinion, a very fair exchange and you can access all those guides here:

http://www.makeuseof.com/pages/download

There is also a link to the excellent MakeUseOf Cheat Sheets on the site. 
I hope this helps you!