I like to read books and I also like to read nonfiction books and in particular nonfiction books that I do not agree with.
For this I've decided to look into speed reading. It is an umbrella term for methods that increase your reading speed while keeping a satisfactory comprehension level. A usual reading speed is 200-300 wpm (words per minute). Speed reading advertises increasing your speed to > 600 wpm.
I've searched around for a bit and read lots of blog posts and articles and here are my favorites:
http://www.fourhourworkweek.com/blog/2009/07/30/speed-reading-and-accelerated-learning/ is a good introduction to the main techniques of speed-reading. It also includes some exercises and is a short read.
http://noahfleming.com/blog/speed-read-like-rain-man-75-increased-reading-speed-in-20-minutes describes the author's personal experience with fourhourworkweek's article.
There is also speed-reading software available. The idea is your eye movement is the main hindrance to reading really fast, so this software displays the text for you to read in groups of several words in the center of the screen. This way you can read everything at once without having to move your eyes at all.
As crazy as it sounds, it works to a great degree.
http://www.spreeder.com/ is an online reader that works this way. Give it a try! You can make it display the introduction text at 600 wpm or 800 wpm and see how you'll understand - you'll be surprised!
'The Speed Reading Workbook' is what I've been using to practise it. It's okay written and has plenty of exercises and includes timing and evaluation sheets, which are really useful for measuring your progress.
A good summary of many concepts can be found in the PowerPoint Presentation 'Double your Reading Speed in 25 Minutes'.
About Reading in General
http://www.matthewcornell.org/blog/2006/2/26/how-to-read-a-lot-of-books-in-a-short-time.html is a good read and http://pne.people.si.umich.edu/PDF/howtoread.pdf has many good suggestions about how to increase your reading productivity.
I've been exercising with the workbook now and then for the past weeks and I've become faster but this is still an ongoing process for me, so I'm going to blog about it later (or rather update this post).
For what it's worth: my reading speed was 300 wpm and now it is around 550 wpm