Lights can add so much to your apartment. Sure, you could stick with the simple overhead light that comes installed in your place when you move in, but how boring is that?!?!
Now we must keep in mind that most apartment communities will not allow you actually install new fixtures, so thinking outside of the box is the key in good lighting. One note on this however, is to ALWAYS check with you management first. They may actually let you purchase a fixture and then have their maintenance team install it for you. Remember that if you do this though, they more than likely will require that you leave whatever item that you install when you decide to move out.
Rather than installing new fixtures everywhere, why don't you try a few of these ideas:
Colored Bulbs- You can accent a number of different things just by changing the hue of the light striking them. The easiest way to do this is to change to a colored bulb. It will not only accent objects that the colored light reflects off of, but will also very much set the mood. Want a cool, relaxing vibe in a room? Try a light blue or aqua party bulb. Want to add that dark, mysterious, and naughty mood? Try a red bulb. Yellow and orange will give off the feeling of warmth as well.
Floor Standing Lamps- If you need more lighting because a room is too dark, nothing compares to floor lamps. They are cheap, easy to move, and some of them look really really cool. You could even try the colored party bulbs in these! My favorite are the multi-bulbed ones that you can shine the beam in several directions at once. Place a plant in front or around and you can create great shadows.
Light From Low- Another really fun lighting idea is to flood a wall with light from below. Usually you would need to go with a type of light that floods upwards. This could be a sconce, a flood, or an upside down desk lamp...virtually anything that flows light across your wall. Be careful when doing this that you aren't using a light that gets hot or could start fire. Be very, very careful.