I have over 10 sites and I can write a Content for each one for full month in less than a day including the 10 promotional articles for each one!
O.k. Let's face it. You need to have an updated site each day, otherwise Google will consider your site and old site. In order to do this, you have to do some research. What the people want? why do they want to know that? what is the why's behind the answer?
One great place that has the question and answers is the Yahoo answers. But doing a reasearch for each site to come up with unique content is time consuming.
However, I found a plug in for Worldpress that solved my problem! It is called Caffeinated content and here is a link to Video.
Caffeinated content is by far the best tool to get the unique content quickly!