How about if a hardware chain used satellite imagery to detect new structures being built, like sheds, barns, etc, and mailed targeted coupons out to the property owners?
That said, we already know they're trying their damnedest to track just that.
Planning applications are available for viewing at the local planning office but they are not available online (though I know a guy who works at the local council who is pushing for them to put all their data online as part of the open government initiative so change is slowly coming here).
For instance, in my state and/or township one can go to township office and request a copy of all the property taxes for any piece of land, no matter who owns it. It costs something like ten dollars and in return you get a hardcopy with a bunch of numbers on it.
Assuming the process for getting copies of new permits is similar, the biggest downside is cost for the information and paying for some intern or whatever to type it in. Even if it's five dollars plus intern is decent chunk of money (I have no idea what the profit margin is on lumber, etc). And then you have to factor in the cost of the promotion which will eat into yet more profits.
Such as when they file a building permit request. Which I suspect may be public information in many jurisdictions.
Also - the gold coupon is the 10% off one from Lowes that comes in the US Postal Service change of address packet.
I think useful permit indicator is to look at recent past permits. Neighbors tend to be inspired by their neighbors to do long-needed projects. As soon as I started talking about doing work on my house, other neighbors started asking for the name of my contractor and started talking about how maybe they should "fix up that garage, or re-do the kitchen."