...Just to one up Val.
Seriously though. We have a good 1/2" gap between our back door & the threshold. There is a storm door on the outside too, however you can see light under it. I've always had a "draft stopper" there to take care of this, but I picked up a proper door sweep at Lowes, it took <5 mins to install & it makes a world of difference. Comparing the before & after, there was literally a breeze coming through that the "draft stopper" did not stop. I'm going to be very interested to see what kind of difference this will make to our gas bill. Surely $10 worth.
Oh and I love this forum, sorry I don't post much.