yeah, it's easy, for the most part. All you need is a webcam that you buy at your local computer store (mine was about $60 USD), connect it to the computer, and most software that comes with it will stream online for you. If not, there are other places out there that create software to stream online with - I use the stuff at coffeecup.com when I use mine.
If you're taking the camera out of the room with the computer, they sell wireless cams, mountable cams, etc... but they're all pretty expensive.