Rob asked the question "Are books dead?" and I thought that I'd spend a few minutes talking about how the market is changing in perspective of technology and learning material.

Firstly, human beings have three primary ways of learning- sight, sound and touch/do.  Typically we are more proficient in two of these and weak in one.  Our preference also tends to vary a little depending on what is being learned.  For example, driving is something that most people learn easiest by doing, where time management is something that I find difficult to learn by doing - unless I've taken in some information to help me with it.

Anyway... when it comes to learning academically we tend to learn best by reading and listening. 

Thanks to the MP3 format and the Internet, it is now easier than ever to grab good quality information and listen to it.  If you restrict your listening time to when you are at church or a weekly bible study (assuming you actually listen), you are really missing out.

There is lots of time in our days where we have time to listen.  I tend to use the time I spend driving listening - driving doesn't require exclusive mind share, so this is pretty easy.  You may also find things like doing the dishes, making dinner, walking the dog, jogging all times where you could be listening. 

There are distinct disadvantages to video that don't exist with audio.  Try watching a video while you drive the car or do the dishes - we (perhaps I) find it difficult to watch, listen and do something all at the same time, but listening and doing something are entirely possible.

On the subject of books, In many situations you could select listening over reading, particularly sermons, but with digital libraries books are changing.  The days of reading books from cover to cover is disappearing (apart from novels), but until technology is able to manipulate audio the way it can text, there will be a place for text.  There are some key advantages that text has.  Specifically you can:

• search it easily (this is a really big deal)
• leave it open while you take it in (as opposed to rewinding it continually)
• copy and paste it easily into other contexts (e.g. blog posts)
• you can skim it and read just the bits you are interested in (much easier than with audio anyway)
• It can be displayed on a wider variety of devices meaning you reduce dependency on audio subsystems, suitability of times to take it in, etc
• You can mark it up (highlight key phrases, etc)

All these things are highly relevant in terms of taking information in and all these things are available in major Bible software and library applications today.

If you are looking at putting together a book today that will be published digitally or even if it wont be, consider how you expect the book to be used.  Theology books such as the Moody Handbook of Theology (also in electronic format here) are good examples of how a book can be organized well for online or offline use.  It is very easy to find just what you are looking for as it is broken into short well indexed components that are easy to absorb in about 5 minutes or less.  If you have long wordy chapters people will read it once and then put it on the shelf and not refer to it again because it would be too hard to find the specific piece of text they were looking for.  This doesn't mean that you can't make long complex arguments in books - rather that the arguments should be broken into smaller discrete components - which people will find easier to understand anyway.

I hope Phil Johnson reads this ;-)