Here's all you have to do. Most MLS systems provide a daily report of recent activity, such as new listings, expireds, sold, etc. Most of us look at this at least every few days, if not daily. Use the data it's showing you to inform your blog subscribers.
An example: We're in a declining market right now. I just noticed that there were 39 listings that expired in the last three days, while only three new ones came on. The blog post gave those numbers and speculated that maybe our higher-than-normal inventory is about to come down a bit. I said that I would monitor it and see if it's a trend. That's the part that should encourage a visitor to return or subscribe to the blog RSS feed or email newsletter.
