There's one simple step that doesn't mean losing your entertainment or spoiling your driving enjoyment, and makes driving safer rather than more dangerous as well as improving your mileage: check your tire pressure.
Good point, that's also a great way to improve it. Good thing improvements are cumulative.
I'm not an expert on automotive engineering, but I don't think removing any electrical component from your car will increase fuel mileage. Most cars have the serpentine belt on the engine also connected to the alternator, so the alternator is always spinning, regardless of how much electrical juice you are using. However, if you have a hybrid, I can see where using less electricity would increase your fuel economy, this is why the new Toyota Prius has solar panels.