My house was built in the late 60's and was always cold. I had seen some articles online about the lack of or improper insulation under the floors of cantilevered rooms. Since half of the front of my house is cantilvered, I figured it was a good possibility that this was my problem, so last spring I decided to see if there was something that could be done about it. This process took several weeks of evenings/weekends to complete, but some time was added because I ended up doing more that just the insulation. Here's a two part video showing how I sealed up the cantilever. If any part of your home is cantilevered and your home is cold, I'd highly recommend checking your insulation. The videos are fairly lengthy, but worth a watch.
Now that it's fall and we've have had a few weeks of "furnace" weather, I can definitely notice a huge improvement in the comfort level of our house. Last year, I was bundled up indoors all through the winter. Now, I can walk around in shorts and t-shirt and be comfortable. Time will tell as far as the heating cost savings go. I'll be tracking that and comparing it to last years heating bills. I'd appreciate your vote in the Winterize contest.
UPDATE (February 2015):
Our full time heat source is a natural gas furnace. It is the only gas appliance in our house. I just received my energy bill for January and my gas usage is 31.9% less than it was at this time last year (see photo). While we supplement heat with a wood burning fireplace insert, we are on track to use less wood than we did last year as well. There's still a lot of improvements that can be made in the insulation of our house, but this was a definite improvement. Thanks for looking and feel free to ask any questions you may have.