You can bring an entire room into the modern age just by changing a light fixture. Do-it-yourself stores have a great variety of stylish, affordable lighting options. It's not hard to change a light fixture -- just remember to turn off the electricity to that light at the breaker box before you get started.
Lighting -- whether it's natural or artificial -- plays a role in the mood of a room, too. You can change the amount of light in a room very simply and economically. Is your room too dark? Consider taking down your heavy curtains or shutters and letting the sunlight in. Going for a romantic look? Use table lamps or floor lamps to put light just where you want it, and replace high wattage bulbs with lower wattage ones for a softer light. Look around for a deal -- you might find a great bargain on a beautiful used lamp at a flea market or antique shop.