if you have a digital camcorder/camera, you may already be able to see IR light (but not a beam). try putting your TV remote in front of the lens and pressing a button... see a flash of light?
If you do, then your camera also sees into the IR range. you can then go out and buy a filter that filters out regular light, and only leaves IR. you can get some effective photos this way. but you won't see a beam this way; for that, follow gen2's suggestions.