5. Good for aiding with temperature regulation in your house. Open 'em when it's hot. Close 'em when it's cold. Works well in tandem with windows (and you're less likely to forget to close them when you go out).

4. Provide privacy when you don't want casual passers-by to see you... working.

3. A good door-slam is a nice way to add punctuation to an argument. Much better than a beaded curtain.

2. Good for slowing the spread of fires through buildings....