If your planning to write a book, you can use a blog to develop content for the book.
1. Participate in the blogosphere: Read and comment on other blogs in your field. This is a prime way to build readership of your blog. It is also a way of getting fresh content for both your blog and for your book.
To check out other blogs in your niche: use www.blogsearch.google.com, www.technorati.com, or www.google.com.
This is also a good way to get ideas. What are other people in your field writing about? What are the major challenges of the people in your field? If you have competitors, check them out. They may be a great help in inspiring you for content ideas, different slants and perspectives. The old song, "Anything you can do, I can do better," comes to mind.
2. Ask readers to comment on your blog. In fact, each time you post something, ask them a question. Then spell it out to them on how to post a comment because your readers will probably need to be educated or at least encouraged to comment. ("Click on the comment link in the footer of this post, and leave your responses.")
Sometimes readers will need assurances of privacy, in which case, you can ask them to email you their questions or comments in private. Others are not worried about privacy because after all, a blog isn't meant to be private. However, readers can be shy about commenting, and need encouragement.
You may also encourage them to respond by telling them that you would like to use their replies in your book, but will only do so with their permission.
3. Survey your readers, do a mini-study on their preferences, their experiences, etc. The Internet is the fastest way to acquire some statistics of readers' preferences. Far from being a scientifically validated study that would pass muster in universities with academicians, an informal survey can give you ideas and material to write about. It can also confirm that you are addressing the concerns of your readers.
4. Run a contest for the best idea, funniest experience, most influential or heart-grabbing situation. If you want to use these readers' responses for content in your book, you should tell them. Many people jump at the chance to be included in a book. Others may prefer to participate anonymously. You can give them both options.
Here's an example of how one writer asked his readers for input:
Do You Have A Broken WIndows Story?
Michael Levine's new book, Broken WIndows, Broken Business is being released later this month. Many people feel this is going to be a mega best-seller.
We have set up a website, where you can rant about broken windows in your everyday experience... Check it out at BrokenWindows.com
People love to share their experiences, and they love to rant, or rave. Just ask.
5. Ask your readers to attend a teleseminar based on the needs, challenges, concepts and ideas of your blog readers. This is a great way to go deeper into the problems and solutions you are writing about. You can record the sessions, transcribe the dialogue, convert the teleseminar to audio and PDF files. These can be sold, or given away as marketing materials for your book.
6. Use your blog site meter stats to examine what are the most popular articles posted. This information will guide you to expand on the topics and subtopics that capture the interests of readers.
7. Consistently reconnect with your passion, and ignite and inspire others with similar interests. After you've been blogging for awhile, you will probably develop good blogging habits:
a. Write something on your blog daily, or at least 2-3 times a week.
b. Read other blogs 2-3 times a week. Be sure to use the My Yahoo or other RSS feed buttons to subscribe to your favorite blogs, or sign up to get email updates through a FeedBlitz service on each blog.
c. Write with your readers in mind. And if you're not sure where their interests lie, ask them. If they've found your blog, and have subscribed, chances are you share a lot in common.
d. If you ever fall into blog-block, reconnect with your core purpose for the blog (remember, the one you wrote out before starting your blog?). When this happens there is usually a reason, although it may not be clear to you at the time. This will pass. You can help it along by asking questions – of your readers, yourself, your closest allies.
8. Podcasting – Create audio files easily by scheduling teleclasses and recording them. Some people like to get their information auditorily and at their convenience by downloading mp3 files to their iPods.
Use a free teleconferencing bridge line like http://www.freeconference.com to host a call. Record your call, upload the audio file and then post to your blog or podcast using a service like http://www.audioblog.com.
As an added benefit, you can get these calls transcribed; then convert the word doc to a PDF file which you can either give away, or sell, in exchange for people's email address; http://www.CastingWords.com is a fast, affordable transcription service.