Here's a male Ruby-Throated Hummingbird at my feeder, just outside my window. I shot the photo through a pane of glass because last year, when I tried it with the window open, a hummingbird flew right into the room with me. He looked around, then turned and flew out. Thank goodness. I just stared at him, frozen in surprise.
If you're interested in attracting hummingbirds, here's a few tips. They like areas with flowers, obviously, but they'll come to a feeder almost anywhere. Don't be afraid to put it close to your window -- these guys aren't shy. Choose a feeder that has little perches for them so they can land and rest while they're feeding. Also, a feeder with a built-in ant trap on top is a good idea to prevent ants from taking over -- the trap is a little moat you fill with water, which the ants can't cross.
The best food is easy to make. Stay away from the store-bought ones -- the red dye is really bad for the birds. The recipe:
Mix four cups of water and one cup of white sugar. Heat until boiling, then cool.
Fill a clean feeder and store the rest in refrigerator. Every three to five days, bring the feeder in, wash it, and refill. The warmer your temperature, the more often you should change the food. It'll start looking cloudy, or get bugs in it. Never add to what's in the feeder -- it's better to dump what's left and start clean. And that's it!