That is my vote.

You asked for feedback about what to do with your creation…

Number 1 – Don’t keep it to yourself. If it is as good as you say it is, you need to share it with others.
Number 2 – Of course, you don’t want to saturate the market and you don’t dare take business away from your dad.

Now to some of your ideas…

I hate and I mean absolutely hate your idea of creating a bunch of sights to “farm” leads and sell them back to the very agents that created the information to start with! Don’t stoop to that level. And I do mean stoop, just do searches on-line for some of the lead aggregators and see what agents have to say about them.

I guess my preferences would be the following:
-create “something” to add the function to existing WP sites
-the how-to series of videos

Of course, both these options require a bit of “techno-savvy” so may not appeal to as wide an audience as you might like. Another thought is to offer “leveled” service –
-do-it-yourself
-you install
-you design

Just my couple of cents worth of opinion! Actually, I don’t even think this is a product I can use. (Agents don’t have access to IDX!) Of course if you need a beta tester in the mid-west, I will see what I can do to help you ;o)

Great idea!

How do you monetize it? Not sure.

I’m not sure that a video series is the best answer. If I’m going to pay, maybe I’m willing to pay a little more to have you do it or have you walk me through it.

After seeing Dustin struggle with getting Homesyn to catch on, I think you need to realize that the average agent isn’t smart enough to realize what you have done has value.

Mark