[caption id="attachment_5914" align="alignleft" width="232" caption="Sealing The Doorway"][/caption]
If you're looking to save money on energy, take a look at this article from eHow Home:
A cost-effective way to save energy in your home is to fill the air spaces between windows and doors, called weather-stripping or caulking. To weather-strip, place a narrow strip of metal, wood or rubber between a door or window sash and its frame to prevent air from seeping through. Caulking is the process in which you spread caulking material in between doors and windows to fill space. According to "Big Green Purse," if every gas-heated home were properly caulked or window-stripped, enough natural gas is saved to heat more than 4 million homes a year.